Topic: 10 bolt rear end?

[bad78ta]

Ive got a 78 trans am with a 10 bolt limited slip yadda yadda yadda. Im really not sure what gear ratio i have, I was under the assumption it was 373's but its turdy as a automatic honda comin off the line. What i'm getting at is I am getting ready to order 456 gears for this thing. Partly because my rear end is starting to go out and I  need to rebuild it, but What i need to know is if my rear end is the original is it 10 bolt by 8.5 or what. I just want to get these gears ordered so I can tear up some pavement

[RENOVATIONS]

is it 10 bolt by 8.5 or what.

If it's the original differential, yes.

[Grand73Am]

Yes, it's an 8.5" 10 bolt. Hard to imagine 3.73's being slow though. If you're only assuming what the ratio is, maybe they aren't 3.73's. You may already know this, but it's easy to check the ratio. Just jack up both rear wheels off the ground. Put the trans in neutral with front wheels blocked. Turn one rear wheel forward one rotation while counting the driveshaft rotations. Put tape or a chalk mark on the tire and driveshaft to help with counting the rotations. The driveshaft would have to turn 3-3/4 turns with one rotation of the rear wheel to be 3.73's. You might have something more like 2.73's, for which the driveshaft would turn 2-3/4 rotations. So maybe getting 3.42 or 3.73 is all you need.

4.56 will be miserable driving any long distance or highway speed.

[dinky]

I have 4.10 s  in my car .It sits all week and I race it on the weekends .I would not go 4.56 if you use it as a regular driver , 3.73 would be good for a driver. I am at 3000 and over , Drivin Ms daisy 

[rad400]

4:56 is aTRACK GEAR ONLY!

[bad78ta]

Ok and thank you grand73 I did not know that.  I will be trying that. Once I figure out what I'm dealing with Ill figure out what ratio I want to run