ClassicOldsmobile.com - View Single Post - Best Rear Gearing for an OD Transmission?

jonstringer · 05-14-2008, 01:04 PM

In my 1976 Chevy Sportvan SWB, I have a 350ci mated to a 700r4 OD trans to a 3.73 Posi Rear. This combination works nicely on my van, but I need your opinions for my olds.

I plan on swapping my th350 with a 2004r OD transmission. My cutlass S has a 455ci, so I'm trying to mate it to the optimal gearing. I was thinking of going with 3.73s again, but I was told that would be too high. I have trouble getting traction as it is with a 2.73 rear. So I'm thinking a 2004r and a 3.42 posi should behave great and leave me at around 2100 rpms at 70mph. Is my math correct or even close? I want to utilize the 455s low end torque which rocks at highway speeds. I'm open to your opinions and advice. What rear end gear should be mated to a 2004r and why?

05-14-2008, 01:04 PM	#1 (permalink)
jonstringer Member Join Date: Feb 2008 Location: Austin, TX Posts: 31	Best Rear Gearing for an OD Transmission? In my 1976 Chevy Sportvan SWB, I have a 350ci mated to a 700r4 OD trans to a 3.73 Posi Rear. This combination works nicely on my van, but I need your opinions for my olds. I plan on swapping my th350 with a 2004r OD transmission. My cutlass S has a 455ci, so I'm trying to mate it to the optimal gearing. I was thinking of going with 3.73s again, but I was told that would be too high. I have trouble getting traction as it is with a 2.73 rear. So I'm thinking a 2004r and a 3.42 posi should behave great and leave me at around 2100 rpms at 70mph. Is my math correct or even close? I want to utilize the 455s low end torque which rocks at highway speeds. I'm open to your opinions and advice. What rear end gear should be mated to a 2004r and why?