how do I know what series carrier I have?

It is out of an 85 or 86 formula with drum rear, 4 speed at, and an injected 305.

10 bolt too.

 

can anyone help??

 

you can buy gear sets for any carrier in any ratio avaiable. all you need to know is what ratio you have now. look in a catalog and you see x:xx ratio for y:yy and numerically higher carriers. it's that easy, and i figure you're asking because you want to change gear sets.

 

Probably the quickest and easiest way is to check the front of the axle housing on the passenger side for the factory stamp. Bring a scrub pad and lots of degreaser and you'll eventually find it. Match this up to the code in your Haynes manual or other source and you've got the axle ratio. If it's a 3.42 or 3.23, you've got a 3-series carrier. 2.73 is 2 series... just go by the first digit and that's what series you have.

If you have any concern about whether someone has changed the gears before, you can't go by the stamp. At this point, you can pull the cover and count the teeth on each gear, then divide the ring gear by the pinion gear and you've got it. Or, you can spin the tire and compare the rotations to the number of rotations on the driveshaft.

 

Look.

Have you changed the fluid lately? Then you need to pop the cover anyway.

 

I have 3.08's in there. I think I need a spacer because the edges of the teeth are ruined. How do I know if I need a spacer??

I want to put in 3.73 gears. What do I need to do??

 

3.08's, if they are factory, are 2 series. You need 3.73's for a 2 series carrier. Richmond makes em'. Summit racing carries them. As far as spacer, I think you mean shims. You won't know what shims you need until you install the new gears. You will then have to 'set them up' or have a shop do it.

 

Right, you need either the thick gears or a ring gear spacer. I would recommend the spacer, because then you can still use the gears in their intended application; for example, you could get a SLP posi unit (which are all 3 series), and they would fit by leaving the spacer out, where if you use the special thick gears, you're stuck with a 2 series carrier forever.

 

where can you get a ring gear spacer for a 7.5 inch rear?
i looked for over a month and never found one, i'll be pissed if someone proves that there is one availible, cuz it'll mean i bought a second set of gears for no reason

 

www.drivetrainspecialists.com

Go to the GM 7.5 page. about 12 lines down from the top


IK83-0750 $55

 

well thanks for the page, i wish i had found it last september, oh well, did i see correctly on that page that you can buy new clutch packs, and such for the factory posi?

 

Looks that way... I don't know too much about that though