Rear gears
 

Taking my Suburban in tomorrow to get the rear gear changed from a 3.07 to a 3.42. The lil 307 engine needs a few more RPM's when the 700r4 is in full lockup.

Re: Rear gears
 

I hope that takes care of it for you. I had a 350 crate engine and 2004r in my '69 Suburban with a 3.08 rear. Transmission overheated and blew the fluid out of the front seal when it had been locked up for quite a while, on a long trip. (250 miles) The bottom side of the truck and back window were coated with trans fluid.... I put a 3.73 gear in it and never had any more problems with it after that. Let us know if the 3.54 works OK for you.

LockDoc

Re: Rear gears
 

The swap to a 3.42 may not give you that much of a noticeable difference. You're only talking an 11 percent difference. 3.73 (18%) would have been a better choice unless you drive 80-85 mph all the time. 3.73 in overdrive will give you about a 2.72 final whereas the 3.42 takes you to a 2.49 final. 4.10s get you closer to the original 3.07s at a final of 2.99


Something to think about---talk to your gear guy and see what he says

Re: Rear gears
 

Going from a 3.42 to a 3.73 in my 94 with 32" tires gained a little over 100 rpm. Right where I wanted to be. Around town results are very noticeable and the trans does not go in and out of OD like it used to on the highway. Did not look at any calculators for your situation and no idea about tire size, but would guess about +200 rpms over what you have now. A good gain without the annoying higher rpm on the highway.

Re: Rear gears
 

Not exactly apples to apples but first gen 2wd S10's with the 4.3 and a700r4 used a 3.42 rear and the 4x4's used 3.73's. The 4.3 and your 307 are close in horsepower and and my S10 Blazer weighs in at 3850. So not a big difference there either.
I can say the the 3.42's in my Blazer are a pretty ratio with 700R4. The 30 to 60 mph hard acceration is better than you expect.

Re: Rear gears
 

I would probably go to 3.73 gears....might get more of what you're after. Either way, hope it works out for you sir.