Expert: Matt Lyons - 10/17/2007

Question
QUESTION: i have a 1988 cutlass with a chevy 350 and 700r transmission.i am trying to figure out what is the best rear end to used or what can i put in my rear end to give it a good performance? but i want to be able to drive on the highway.

ANSWER: The housing in your car is a 7.5" 10 bolt. This isn't as strong as the earlier 10 bolts that had a 8.5" ring gear. But it will hold up for moderate street usage. I would suggest that you get a 3.73 ratio gear set and have a competent shop install it for you. Summit sells a Detroit locker differential for your car if it didn't come equipped with positraction from the factory. Just remember to break the gears in slowly and use a good synthetic lube.

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QUESTION: did any g body car come with a good posi rear end beside the grand national, and what year did it come in?

Answer
The GN was the only "performance" rear end that I know of for that vehicle platform. In addition to the Detroit Locker you can also get the Richmond Max Traxx insert for your open differential housing. Much cheaper and doesn't require full disassembly of the rear.