Rear Differential

I got curious after reading the post the other day about lowering rear end gears. I looked into my 1998 K-1500 and found something out of the ordinary. My truck has a 3.42 rear end in it. Finding this out, I now realize why I have no power passing people and less power in general than other trucks equal to it. After speaking with some buddy's on this, none of them had even heard of GM putting a 3.42 rear end in their trucks. I was just as suprised as they were. Is this a common rear end? Would it be a good idea to change to a 3.73 or a 4.10?

I'd never heard of it either, but I did a search on Google, and it does exist. I didn't look closely at the results, but ut looked like all of them were on muscle cars. Type "3.42:1 chevy differential" in at www.google.com to see the results I got.

If it were my truck, I'd spend the money I would spend to regear on getting more horsepower out of the engine.

I know a lot of new chevy trucks have the 3.42 rearends in them. Good gas mileage anyway.

The 2005's have two choice's of ratio's 3:42 or 4:10 . This was my options accoring to the fleet manager. He said no longer offer the 3:73 (which I liked the best) so I went with the 4:10.

Mine has 3.08...talk about nutless :(

Mine has 3.08...talk about nutless :(


Yeah...My 86 has the 3.08. Its pretty pathetic.

Most of the Chevy/GMC 4x4's from 1988 to 1999 come out with 3.42 ratio unles you got the towing package from the factory and then it had 3.73 gears and 11 rear drums. The 3.42 is a decent ratio with stock tires if you dont tow that often. Much better than the 3.08 which came in the earlier trucks. I guess if you drove 80mph and up the 3.08's would be fine.

I started to notice that my truck does not have the gitty up that my friends z71's do once I changed to 285/75 tires. I new something was up. When I had the 265's on this truck I would get about 16.5 mpg on the highway. But with the new tires, my mileage is about 13.5. Do you all think that I should spend the money and put a 3.73 rear end in to save gas mileage and increase my power? or should I just leave it alone?

I got the same set up as you but I changed to 3.73 ratio. It drives like it did with the stock tires, maybe a bit better. I think it is worth it if you plan on keeping the truck.

My 94 has 3.73 & bigger brakes w towing pakage also have trans & motor oil coolers from factory.I luv it !!!