[Supe]

Hi all, long time, no Pontiac (my 79 Firebird has resided with my father for the past 9 years now), and I'm now looking at picking up a 73 Catalina with an Air Ride setup on the corners.

Did these come with an 8.5 rear, or were they one of the odd duck "corporate" rears with no aftermarket support? If the latter, are there any alternatives that will actually swap into the big B Bodies? I'm sure as heck having a hard time finding information on the 71-76 B Bodies compared to the F bodies (as though I'm so surprised).

Thanks for the help!

[dedsleds]

8.875 RING GEAR, CANADIAN REAR END

[Supe]

Thanks. Is that a 10 bolt, or a 12 bolt? Do 12 bolt guts fit in those? Trying to figure out if I see a 9" in my future, or if there are aftermarket parts availability for those. Do the late model Impala/Caprice rears bolt in to these cars?

[dedsleds]

I THINK IT IS 12 BOLT GUT IN A 10 BOLT CASE. NO 0NLY 71-6

[Supe]

Sure would be nice if the 12 bolt guts fit in there!

[Racer81x]

Most of the pontiacs had the buick or olds rears, like said earlier: they are bigger than the 8.5's they have a 10 bolt cover but have the 12 bolt guts.

However most of the impalas or caprices from 71-76 had 8.5 10 bolts, which you can eaisly find gears for, I have one of these rearends with 4:56 gears that I use in my fullsize demo cars.

[Supe]

Good to know, thanks. So, 12 bolt guts will NOT fit the 8.875 10 bolts, correct (e.g., I can't go finding 12 bolt posi's and gearsets to swap into this housing)?

Are there any specific 71-76 rears to look for? E.g. factory posi, need a 3.xx gear set to go numerically higher, etc.

Thanks again for the help!

[dedsleds]

POSIS ARE USUALLY 3.08 3.23...............A 3.42 OUT OF 71 CATALINA'S W/350'S AND 3 SPEED MANAULS ARE RARE...COP CARS MIGHT HAVE THAT GEAR. SOME ARE C CLIP AND SOME ARE BOLT IN REAR AXLES.

CHEVY REARS WOULD BOLT INTO PLACE.

['ol Pinion head]

Nearly all '73 Catalina's came with 400 2 bbls & the 28 spline 8.5 c-clip axle B series rear (also used under Impallas)..look for the round cover. Have popped the hoods & pulled engine parts on 100's of 73 Cats. Its very rare to find a factory 400 4bbl or 455 under the hood of this era of Catalina.

The 8 7/8 MP series rear was used under Pontiac B series of this era with 455's. This style rear uses a 12 bolt design ring gear, but its gears & posi unit do [b]not{/b] interchange with the common 12 bolt chevy car or '64-81 12 bolt chevy truck rear. Factory posi units for the '71-76 8 7/8 MP series rear are not that hard to find for the high ratio gear, but harder to find for the more desirable low ratio gears like 3.23's. 8 7/8 MP series rears for this body style will use 31 spline side gears for the rears c-clip design axles.

[Supe]

Much appreciated, Pinion head. This car is indeed a 400 2bbl. I will give the owner a call and ask if he can snap a pic of the rear end cover. I'd be delighted if it was indeed the standard 8.5 rear.

[Racer81x]

If it's the 8 and 7/8ths 12 bolt, the best car to look for with the best gear would be a 71-72 or 3 Buick rivera GS, most of them had 3.42's, which is the lowest gear you can get for one of those style rear ends.

[Supe]

Great, I'll have to have some of my junkyard buddies keep their eyes peeled! Thanks.

[grandville455]

Originally Posted by Racer81x

If it's the 8 and 7/8ths 12 bolt, the best car to look for with the best gear would be a 71-72 or 3 Buick rivera GS, most of them had 3.42's, which is the lowest gear you can get for one of those style rear ends.

Correct, but only the 71,72 had the 3.42 the 73 had a 3.23, I still have my buick rear, but the ring gear was destroyed,along with the pinion,Do Have a ring gear ,but someone would have to find the pinion,It was in my grandville for yrs..They are a very tough rear and i put that thing thru the tests over the years!

['ol Pinion head]

'71-74 Buick Riv's, Centurians, & other 455 powered big Buicks of these years used the BUICK 9 3/8 rearend. Bolt-in axles, very tough rear. These are the rears that the Riv GS's had 3.42's & 3.23's, not the 8 7/8 MP series. also ck the Buick Estate wagons of this era.

Sure miss the days these big boats hit the Pick-N-Pulls, I was usually one of the only ones pulling drive train parts from them.

[Supe]

Got a hold of the owner last night. Explained to him the differences between the two covers, and he described it as "round, evenly spaced bolt holes." So, it sounds like OPH was correct - should be a normal 8.5 10 bolt.

Man, it's getting harder and harder to justify not buying this thing...