Im looking at a 3:91 posi to act as a starting point for my 70 Cutlass S. The original 350 will be rebuilt to 350+hp. 3:91 is alot more gear than i wanted, but the car is so big and heavy i think it will really wake him up. I just dont want to lose hwy cruisin. Will a 200r4 handle that hp and maybe go to the strip, while providing the overdrive? Thanks

 

Oh yeah, will my driveshaft still work? Not sure if theres a difference between my 70 and the pre 70 it came out of. The casting code is 394139 with 31 spline. Thanks again!

 

I use a 2004r with a 3:90 gear, it works fine, I wouldn't drive 85 MPH all day but 65-70 works fine. As far as HP capability a 2004r will handle 350HP just fine as long as it's rebuilt and upgraded for it and yes your driveshaft will work.