I want to get a new engine in my 97 K-1500 and all the research that i have done up to this point has lead me to believe that 6.0L should fit right in place of my 350 and bolt up to my 4L60E tranny w/o problems....sound possible? There is not a thing wrong with my engine now other than i am not satisfied with it's power. it has nearly 114,000 miles on it and i had the the dealer put new head gaskets in it when i purchased it and i have had no problems with it at all. All i want i a factory 6.0L, i would prefer it be new but if a good price was given on a used one i wouldnt pass it up. So i guess my questions are how easy would it be to do and how much would it cost?, taking into account that i would be "trading in" my 350. Also what is the difference, in cost, between the 6.0L that makes 300HP and the one that makes 345HP? Money is the main concern in this project. Any and all input will be appreciated.

Any knowledgeable advice out there? Slowprocess...?

Any knowledgeable advice out there? Slowprocess...?

Yeah, man, I can help you out here. Allen Nelson, my tuner and owner of Nelson Performance installed an LS1 into his 94 Chevrolet. I'm going to post up his explaination and recommendations, since you will go through most of the same obsticles he faced. This install goes for the 4.8L,5.3L, and the 6.0L as well as the LS1. Hope this helps you out, man. :)

I would have to say the most important step indoing a swap is having a plan. Before you start the swap, get all your parts on paper and a rough plan together on how the engine will be removed and the steps for the install. Now that your parts are in order and you have a plan of attack, plan on this project taking anywhere from 1-6weeks. Trust me; you’re going to run into small hurdles during this swap. You can say it’s going to take you 2 days but I guarantee it will take longer.
Some parts you are able to use from your swap are: radiator, hoses, wiring, battery cables, shroud, power steering hoses, driveshaft, starter wiring. I’m sure there are more parts, but these come to mind. You are not able to use your older TBI Vortec accessories or parts. The LS1 is not interchangeable with the older engines. The engine mounts will not work without modification. The starter will not work, nor will your earlier style 4L60E/700R4 transmission work. You may choose from the f-body or truck harness or buy a custom wiring harness for your install. You will use bits and pieces of your old wiring engine harness. The LS1 harness only needs a few ignition hot and constant hot fused power wires to run the LS1. I elected to purchase the Painless Wiring auxiliary fuse box to hook all my harness wires to. It consists of 4 ignition hot and 3 constant hot all triggered by a relay. It makes the install and wiring nice and simple. For starter hookup, use your existing PPL (purple) wire coming from the firewall. This will power the solenoid once all the battery wiring is in place.
Engine mounts will have to be fabricated or you will have to modify your existing mounts. I’ve seen both ways done. I elected to make my own, strong as hell, brackets and weld them to the cross member. If you are going to make your own, you’re going to have to test fit the engine several times before you get the mounts and engine lined up just right. Use chalk to mark the locations of the mounts.
If you want air conditioning you have three choices. You will have to notch your cross member, you will have to fabricate an ac bracket to move the compressor to another location, or purchase the bracket and compressor from http://hotrodlane.cc/. Most are not comfortable with cutting the cross member up, but making a bracket isn’t as easy as it seems either. I’m in the process of making a bracket out of aluminum that will move the compressor above and next to the passenger side cylinder head. I also purchased an additional pulley to route the belt. A custom belt will have to be purchased in order to turn the compressor. Mine came out to 115.2 inches. The same belt will power the compressor and all other accessories. I wanted to create a setup that allowed me to use the original belt tension pulley also.
Your driveshaft will slide into the new auto or manual trans. The TH400/350 700R4 and 4L60E use the same spline for the trans yoke. I had to have mine lengthened just a tad to have it fit just right. If you mod your original engine mountsyou should be ok. I relocated the engine, that's why mine was made longer.


Installing an LS1/Truck Wiring Harness

I'll try to explain how to install a stock 99-02 truck harness into your previous gen. (94) Chevy/GMC truck.

First, I'll list the things you will keep in order for everything to work properly. The fuel relay harness is somewhat separate from the main engine harness. You'll keep the relay and all the wiring that is connected to it. Wiring for the fuel pump, fuel pump fuse and PCM signal wire will remain. Remove the main engine harness by disconnecting all the engine sensor connections, the PCM connections (mine was under the glove box), the transmission harness connections, the battery connections, all grounds, and any other miscellaneous connections not mentioned. Don't be afraid to cut the harness and connector wires that you can't easily get to, just leave enough wiring on the end of the connector in case you need that connector later. Your engine bay should be clean of the engine harness. My truck has a junction block that has five terminals that are used for power. It's located on the firewall near the AC accumulator. I chose to run a 4 gauge cable from the battery to this block. Later, you may need to power relays and accessories on the passenger side and it's more convenient and cleaner to have power on the passenger side.
Your harness will come with a big blockhead on the end of the harness that normally connects to the firewall or another harness on the newer trucks. You will cut that block off and have tons of loose ends, do not be discouraged. You cannot do this with out a pin out. I have a pin out for a 00 truck harness, contact me if you want it I can fax it to you. All of the pink wires are 12+ for sensors, if not, oh well, mine are still working. Gather those together and tie wrap them. You'll notice a few red power wires. Determine which one is PCM power and connect it to constant fused 12+. A 20 amp fuse will do. This is like the memory wire for radios, the PCM needs 12+ all the time so it can keep it's memory. The other red ones are ignition on power; hook those up to a fused 12+ when the ignition is on. Ten amp fuses should be enough. The black wires are ground. Provide a good ground or you'll be sorry. The grounds on the truck should be like this. Connect a good heavy ground from the battery to the engine block or alternator bracket(the negative power cable). Connect a ground strap from the engine block to the frame. Connect a ground strap from the frame to the body/firewall. I also recommend connect a 10 gauge wire from the battery post to the side fenders. Do this and you will not have any grounding problems.
Going back to the pink wires. Connect these wires to a fused 12+ when the ignition is turned on. I chose to use a painless performance fuse block. It has four ignition hot and three constant hot fused outputs. I connected about 4-6 pink wires together and then connected them to one of the ignition on wires. That is all it takes to power the sensors/injectors/etc.
The two or three red wires that feed power to the PCM areconnected to the other ignition on wires, from the painless fuse box.
If your truck is a 96 or newer your ALDL connector is ok. This connector is used to read trouble codes, reprogram the PCM and for diagnostic programs. It is almost always under the dash near the steering wheel. If you have a 95 or older you'll need to get a newer connector. The junkyard is a good source and you can just stick it in your pocket, lol. The only wires needed in order for the ALDL connector to work are 12+, ground, and the signal wire.
For my application, after I removed the engine harness I had to rewire the rear lights. I can't go into much detail on this step because I'm still having problems with mine. Sometimes the blinker works and sometimes it doesn't, depending if the brake light is on. You're on your own on this one. I don't think it's hard, it's just not on my list of things to do right now.
The PPL, purple, wire is coming from the ignition to the starter. It charges/activates the solenoid which in turns powers the starter gear. The new truck harness will come with one or you can opt to use your existing one. I chose to use my existing one since it was already wired up to the ignition. I just trimmed the new PPL wire from the new harness and connected it to the existing PPL wire coming from the firewall. The tan wire coming from the firewall is the oil pressure gauge wire. The stock LS1 oil pressure sensor will work with your gauge. It may read one mark higher, but it's just fine for me. The temperature gauge is a different story. The LS1 comes with a two wire temperature sensor. Your truck will have a three wire sensor. These sensors are not compatible or interchangeable, but you can purchase a three wire sensor from your LS1 swap manual. It has three wires, one for the power, one for the PCM and one for you gauge. My gauge doesn't read correctly below 120 degrees. What I did was get the engine up to normal operating temperature and remove the needle from the gauge. Then replace it making sure it's reading the correct temperature. It now reads correctly up to 210 degrees. I didn't want to test it above that temperature. Buy some wire loom and wrap up all of your wires. I used electrical tape first, then wrapped the wire with black loom.

Wow man thats a lot of info, however to me its almost jibberish. I'm a plumber and know next to nothing about engines. In your post it says a 4l60e will not work but i see that is what you have in your truck, so will mine (1997) work with this engine? If not there is little chance i will attempt this cuz money is tight. All i want is factory replacement, rebuilt or, even a slightly used 6.0L engine. Again cost is the main concern. i would be selling my engine and looking to pick up a 6.0L for the best price i can find.

Wow man thats a lot of info, however to me its almost jibberish. I'm a plumber and know next to nothing about engines. In your post it says a 4l60e will not work but i see that is what you have in your truck, so will mine (1997) work with this engine? If not there is little chance i will attempt this cuz money is tight. All i want is factory replacement, rebuilt or, even a slightly used 6.0L engine. Again cost is the main concern. i would be selling my engine and looking to pick up a 6.0L for the best price i can find.

Sorry about the long post up there man. :grinyes: Both of us have 4l60e trannies, but it is my understanding that there are differences in the 4l60e that hooked up to the 350 and the 4l60e that hooks up to the Gen III engines. I'm sure it's something in the way it hooks to the motor itself. Best bet would be to find a complete pullout, including the motor,tranny,computer,accessories. I've seen them go fairly cheap, but it's all about locating them. I've seen plenty go on ebay. Mostly LS1s out of camaros,corvettes,trans ams. Great deals are out there.

On a side note, have you thought about an LT1 350? The reason I ask is because I have a good friend locally that has an older body style stepside with the entire drivetrain from an older vet with the LT1. It's a pretty damn quick truck(13 flat), and it seemed to be a fairly simple process in installation. He installed the rear suspension from the vette as well, and it is truly sick as hell! I'll have to get some pics next time I see it. It would probably be a whole lot cheaper going that route, and it would be alot more simple.

Hey man, you really know how to help someone out, thanks. ok maybe i need to broden my options beyond a 6.0L then. What i want is an engine to put me in the mid 15's with above 300Hp. The truck would primarily be used for offroading more so than racing for anything other than regular driving. I would prefer to get an engine that will hook right up to my tranny no problem but if i came across both for the right price i wouldnt turn it down. Maybe the place to look would be around engine shops lookin for something rebuilt or used. As far as i can tell it would be cheaper to get a new engine than juice mine up, but if thats wrong let me know. I am in no hurry to do this until i see exactly what i want.