How good or bad are cutlass rear ends

[-83MONTESS-]

If you are looking at 400hp I think you could get by with a 7.5 with good axles and carrier. The only 8.5 that will bolt directly in would be from an 80s 4-4-2, H/O, or Buick GN. There are some people here that drag race consistently with a 7.5 and there are some people that claim you can break them just by looking at them wrong so who knows for sure. I have been abusing the hell out of my 7.5 behind my mild 400 for going on 4 years now with no issues.

 

[skulledmonte84]

If you are looking at 400hp I think you could get by with a 7.5 with good axles and carrier. The only 8.5 that will bolt directly in would be from an 80s 4-4-2, H/O, or Buick GN. There are some people here that drag race consistently with a 7.5 and there are some people that claim you can break them just by looking at them wrong so who knows for sure. I have been abusing the hell out of my 7.5 behind my mild 400 for going on 4 years now with no issues.

I often wondered about that,i am still running the 7.5.too id like to get at least get a posi an good axles though,iv had enough of the "one tire fire" but if i ever do get a chance at an 8.5 for good deal i am goona grab it up.8.5 should be more than enough for a stock 350/700r4 with cam,headers,intake,carb,roller rockers not going to be beating the dog sh*t out of it,well only if i am piss off lol

 

[skulledmonte84]

Lockers make noise but they also "unlock" during cornering so you dont eat up tires or snap axles. In straight aways they act the same as a spool. IMO this is the way to go. I wouldnt bother with a 12 bolt because of the widths and the need for conversion control arms when you can spend the same amount of money on an 8.5 and have it bolt right in(with a 1" shorter driveshaft).

I changed my trans from a 350 turbo to a 700r4 an had to cut the drive shaft down to fit the 7.5 rear.So if i change the rear to a 8.5,is it going to be too short ? i just want o make sure,If so i'll just get another drive shaft an cut it down 1" ? i can't remember how much was cut off though

 

[pontiacgp]

if you change from a 7.5" to an 8.5" then you will need to take an inch off the driveshaft

 

[skulledmonte84]

if you change from a 7.5" to an 8.5" then you will need to take an inch off the driveshaft

The drive shaft has already been shorted for the 700r4 swap,It's going to be too short if i cut it again,Right ?

 

[pontiacgp]

if you change from a 7.5" to an 8.5" then you will need to take an inch off the driveshaft

The drive shaft has already been shorted for the 700r4 swap,It's going to be too short if i cut it again,Right ?

it doesn't matter what transmission you have, if the driveshaft fits with a 7.5" rear then your need to take an inch off it if you replace the rear end with an 8.5"