Jhucks03

Would a gear set out of a later model GM half-ton truck work in my ’71 Cutlass? Both are 8.5” 10-bolts right?

Cutlass rearend doesn’t appear to be a Type-O. Does have bolt-in axles.

Thought I might could hit up the pick-n-pull and snag some
gears and a limited slip.

joe_padavano

The 1971-72 rear axles are "corporate" 8.5" ten bolts, except that they have the bolt-in vs c-clip axles. Any internal parts (gears, bearings, posi) that fit the Chevy 8.5 car axle also fit this. I don't know enough about the truck axles, however, to say they are the same as the car axles.

Fun71

Richmond Gear's web catalog shows all the vehicles with compatible ring and pinion gear sets:

https://www.richmondgear.com/wp-cont...n1.pdf#page=31

joe_padavano

Unfortunately, stuff like this always makes me skeptical of the rest of the info in that table...

monzaz

ALL 8.5 gears are the same.
Will interchange in all 8.5 10 bolt corp. rears.
10 bolt cover 10 bolt ring
Posi units too will also interchange not a problem....BUT you DO NOT WANT a truck auto locker GM limited slip posi unit locker....THEY asre NOT designed for car type playing.
They are low speed operation units 30 MPH and under
over that they do not lock.
So do not bother looking for the TRUCK posi.
You want car unit or aftermarket posi units.
NOW AFTER many years gone by...there are some pick apart trucks that I HAVE SEEN car units in them as guys transferred




over to them and or aftermarket if the stock unit blew up ....SO do open them and check.
THe Auto locker is NOT a bad unit...IT IS just not made for burn outs and fun stuff we all like to do with the cars.

THESE ARE ALL GOOD UNITS IF THEY LOOK LIKE THIS GRAB IT.

Jim Mitschke
JD Race

Jhucks03

Good deal. Thanks for info. Went and scouted out today. Grabbed a supplemental electric vacuum pump for brake booster.

Counted at least 5 8.5” 10-bolts with 3.73s and G80 locking rearends. Going to get 1 tomorrow.

Is the pinion yoke same spline, etc.

Fun71

Well, to be honest I haven't personally seen a 70-76 F-65 so I have no idea what rearend would be under one.

bigrbandit

On the trucks, up to 88 has 28 spline count, 89 up has 30 spline axles, so the majority of them in the junkyard now won't work for you.

joe_padavano

The original question was about gears, not posi units. Axle spline count has nothing to do with the ring and pinion.