Hey guys, I知 currently swapping in a ls1 into my 1987 manual v6 RS. I知 wondering if anyone knows the gear ratios in the the rear and if so do you recommend keeping them or swapping them out? Thx

 

Could be 3.42. I would consider that the absolute bare minimum. But of course there's ALWAYS more to the matter at hand than the overly simple.

You'll probably want at least 3.73. Kinda depends on what transmission you end up with. Maybe even 4.11 or higher.

And of course, a good quality posi, 28-spline axles, and better brakes than those old dumbs ... exCUZZZZE ME, ... drums.

 

3:42 will work but the 3:73 would work more effectively. A friend installed a 200-4r in a '67 El Camino & used a 3:42 gear but soon changed it to a 3:73 because the 3:42 caused to many down shifts. RPMs were too low.

 

Ok, sounds like I値l stick with the 3.42s for now. I知 just in the business of getting this thing moving, and after that I値l fine tune everything.
Thanks guys

 

Get the new motor in and use the existing 3.42 rear (assuming that's what it is) for now. 3.42 is an OK gear for a stock LS1 and will work fine, but not optimal. The 4th gen LS1's with T56 6-speeds came with 3.42 rears. They were OK (compromise of performance and gas mileage), but a 3.73 or 4.10 would have been better. The open diff would be a bigger issue for me than the 3.42's, so when you're ready, do the gears and a good posi at the same time.

 

Sounds like a plan. Thanks