ive got a 9 bolt .277 rear gear ratio in my 89 formula 350 and im gonna change it to 373......can anyone tell me about the rear end i have now.26 spline?...30 spline? my posi unit works great so im not gonna change it...does anyone have any info about where i can get a good cheap set of gears for this car that will work in it? anyone?

 

use 9bolt AND 3.73

 

does a 373 require a 3 series carrier or can i get a 373 gear and pinion that will fit what i have?......thanks

 

twelve.

 

AFAIK there are no "special" thick gears available for 9-bolts, and no ring gear spacers either.

You'll need the right carrier.

All that about spline counts doesn't apply. That's 10-bolt stuff. You have a 9-bolt, and all of them are the same in that regard, so just make sure you buy 9-bolt parts.

 

a buddy of mine has a rearend out of his s-10 that is all new....he wrecked the truck and might sell the rearend out of it and it has 355 gears with a new posi unit........will this fit in my 89 formula?......thanks

 

No.... the S-10 has a 10-bolt; and in any case, it won't bolt to one of these cars, because it won't have the torque arm provisions. But if you had a 10-bolt, the gears out of it would fit your F-body 10-bolt, although I'd throw that crappy Eaton Gov-Lock (if that's what he still has one of) in the trash.