The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Trying to figure out if I will need to regear my rear end

tim_mc · 02-25-2023, 10:44 AM

I'm running a 700R4 and had my diff rebuilt from 3.08s to 3.42 due to some lugging at lower speeds and a few too many downshifts on the highway. In all honesty, I was looking for an excuse to put in a posi rear end. I mostly scoot around locally and wanted better acceleration but didn't want to pull too many RPMs on the interstate. With 3.42s I'm cruising 70 MPH on the highway at 2000 RPM with a tire size of 235/55R17 (~27"). Like Jason and a few others suggested, I would try the 3.08s first as it may be perfect for your driving needs.

02-25-2023, 10:44 AM	#12
tim_mc Registered User Join Date: Jan 2019 Location: St Peters, MO Posts: 461	Re: Trying to figure out if I will need to regear my rear end I'm running a 700R4 and had my diff rebuilt from 3.08s to 3.42 due to some lugging at lower speeds and a few too many downshifts on the highway. In all honesty, I was looking for an excuse to put in a posi rear end. I mostly scoot around locally and wanted better acceleration but didn't want to pull too many RPMs on the interstate. With 3.42s I'm cruising 70 MPH on the highway at 2000 RPM with a tire size of 235/55R17 (~27"). Like Jason and a few others suggested, I would try the 3.08s first as it may be perfect for your driving needs. __________________ 1967 C20, 350 SBC w/Comp roller cam, 700R4 w/3.42 posi, PS, 4-wheel PDB, Old Air AC & GM Tilt column.