lower rearend gears

Looking at the glove box sticker on my 1986 k10 4x4 I see it has a .308 rearend ratio. Thats probably why it shifts out of overdrive so much trying to keep 60 mph. I thought it was just nutless. So my question is if I change to .373 or maybe even lower like a .410, do I have to change gears in the front diff or will it be ok in 4 wheel drive leaving the stock gears up front?

You have to change both front and rear gears or you will shell out everyting in between.

unless your not going to use 4wd

its my hunting truck so 4 wheel drive has to work. I was pretty sure I would have to replace both since it costs about $200 per axle. Thanks guys.

Having 308 gears is bad, you probably want to go with 3.73 or 4.10

yeah..in 1st and 2nd gear it has plenty of power but in overdrive, any time you give it a little gas it has to shift down. I'm planning on using my tax return to rebiuld the tranny and will probably go with 4.10 for some serious power.

Yes it makes a world of diffence I went from 3.73'S and no power (due to tire size) to sports car like accelation and now have the ability to pass uphill now! And I get better gas milage to boot!

My 86 K20 350 does fine with 3.73:1 gears. Just don't go too big or you'll start losing gas mileage.

True, I know on the superlift website there is a link that shows what your ideal RPM's will be according to gear ratio & tire size, It's very helpful in getting an idea of where you want to be in regards to drivability.

I have a 98 K1500 with the high gears and I want to change to a lower gear as well. How much can I expect a job like this to cost?

Not sure since I did mine myslef but the front is a beeyatch let me tell you, Especially if you got a lift because you may have to remove the lower subframe to get that front diff out so make sure the gear ratio you choose Is gonna fit in your long term plans with the truck, In the rear end dept make sure you change rear carrier since they tend to break faily easy. I grenade mine w/35's just cruising thru a parking lot!

Is it fairly easy to do it yourself? If so, what kind of work am I gonna have to put into it?

It's easy if you're good at it. You need to remove the wheels, pull the axle shafts out, remove carrier, remove driveshaft, remove pinion gear. Then get the old ring gear off the carier, put the new one on, and instalation is basically the reverse of removal. You need to check how the ring&pinion track, and make sure you tighten everything to specs.

changing gears should be done professionally unless you want a lot of head aches. Gears, parts, and labor will probable run around 600 per axle.

I recommend you have someone who knows how to set gear lash and set bearing preload otherwise your pinion bearings and gears could have a short lifespan. The rear is fairly straight foward just make sure you loosen the pinion shaft bolt while the wheels are on the ground otherwise its almost impossible to break loose! Depending whcih axle you have will determine what you have to do, full floaters are easier since you dont have to remove the wheels, A chilton manual should help you on this. But the front is an entirely different monster, depending if you have a lift kit or not, You'll have to take out the front diff from the truck to work on it since the IFS set up can't be dissambled on the truck, but remeber to break the pinion bolt loose while the truck is on the ground. I haven't seen a DYI (i.e. Chilton) repair manual show how to rebuild the front diff, You'll probably have to take this to a shop to put the gears in or have someone around familiar with the IFS set up do it, I did my rears but sent it out for the fronts to be done. But if your feel comfortable with doing it, Go for it, It will be good experience to do it your self. There's nothing wrong with learning something along the way!