i would like to upgrade my car's rear end. I have a 323 rearend and would like to get something bigger. My friend has a 370 I think, but i am not sure..I was wondering if there is anything in the middle...I dont like my friends car as much because of the wine he has... What are my options...Also what is the difference between the 9 bolt and the 12 bolt, are there more than that? Whats the best rearend?

 

put in a chrysler 8 3/4 rear end. i custom made one for my 85 trans am over this summer with my grandfather. it came out awesome, and 4.10 are great even with a stock 305 tpi. click my link for pics of the rear end, with the 8 3/4 you can change a center section in about 3 hrs or less.

 

You can get 3.42's or 3.73's that will work in the rear-end that you have.

 

i can get 3.73s for the 8 3/4 and also 3.55, no 3.42, i like 4.10s and since i have overdrive its pretty good, 65 is like 3300 mph .but i dont drive the car daily or very far.so its good for me.

 

if it's stock and auto, go with a simple 3.73 gear swap. If you plan on reaching down, grabbing a pair, and getting some real power, go with a whole rear end swap to a 12 bolt. 12 bolts are alot stonger than 9 bolt, but not as strong as a 9 inch. But if your not making insane power (over 1000), go with the 12 bolt because there is less power loss (about 2%) when going with the 12 bolt over the 9 inch.