Trying to figure a date on this diff, its olds/pontiac. Originally thought 57-58 because the carrier is round and not slightly oblong (at least by my eye) although the flat style yoke is 55 or 56 and older. Has sway bar mounts like olds...idk if the pontiacs had sway bar mounts as well?
Paul posted some info in here that might help you. https://www.jalopyjournal.com/forum/threads/9-3-pontiac-olds-rear-end-hit-a-wall.1201774/
Clean it up and look along the bottom between the bolts for some stamped letters and numbers. Some of them have final build info stamped in. That may only apply to the ‘57-‘64 units but it can’t hurt to look. Post photos of all cast in and stamped numbers that you find. They are all good strong rear ends but ratio choices are slim for the ‘54-56 rears and parts for all of them are getting harder to find.
That rear looks like mine. This one has a 5x5 bolt pattern, massive hangers to adapt it to the Ford buggy spring, and some sort of disc brake conversion. It’s about 59” flange to flange, so probably too wide for a 36. Also has trailing arms mounted to the axle . They have deteriorated rubber bushings. Any idea what this is from? No numbers that I could find. I will probably take the cheap way out and narrow an Explorer or Fox Mustang 8.8 if this thing isn’t fashionable...
If you go this route, I'd suggest the Explorer over the Mustang for the following reason. The Mustang (59" - thru 1993 and 61" '94,'98) has equal length axle shafts and a close to centered pinion. Narrowing the Mustang messes with the more ideal proportions. The Mustang housing fitted with two Ranger long side 5 lug axles provides the 4.5" bolt pattern. Whereas, the Explorer (59.5") has a long and short axle and much further off center pinion in stock configuration. Narrowing it by the popular method of using another short side axle loses about 3" (2.875 IIRC) and brings the pinion closer to centered. Another option is the Ranger (58.5"), which also has a long and short side axle and greater pinion offset than the Mustang. However, the stock short side may be too narrow for you application. Regarding the housing differences, the Mustang 8.8 is the lightest housing (same axle dia. and axle bearings as Ranger. The Ranger has a heavier duty housing than Mustang, but lighter than the Explorer. The Explorer is really beefy and may be overkill for the typical street driven hot rod and the extra weight is detrimental to ride quality. Another Ranger option is the earlier version that is 56.5" width stock. Rangers are available with either 9" or 10" drum brakes and all are 5 lug 4.5" bolt pattern. Ray
Personally i think the olds rear is extremely fashionable as evident by the fact that someone stuck one in my 33 dodge back in the day. If i didnt have a rear i guess id use an explorer 8.8 but itd make my skin crawl. Its just not right, i want to drive a time capsule bumper to bumper...if it even gets bumpers haha. I have an 8.8 id part with for anyone close btw. All just my opinions btw, make yours what you want it to be!
Sort of why I am seeking input. I like the idea of the Olds or Pontiac, or whatever I have. I can live with the fact that it’s an open dif, and, I assume, has highway gears. Not sure how to go about narrowing it , having that stout spring hanger welded on it. Narrowing an Explorer 8.8 seems more straight forward. I also have a Maverick 8” laying around, but that’s destined for my 65 Falcon. Any guesses on what the Olds/Pontiac came out of, given the factory looking trailing arms?
Th Trailing arms are attached to the sway bar mounts. Did you find the cast number like i posted a pic of? In my opinion if you're building a period hot rod ya gotta decide what period you want, i love mid 50s high school/college kid builds so thats the direction im going. If youre building a house you dont just start grabbing bags of concrete and screws from the garage and start building, you make a plan, same concept here
The car’s 2200 miles away, so I won’t be finding numbers until May. I did look previously, and didn’t see any, but you know how that goes. The car seems to be a late sixties or early seventies project that someone started and abandoned. I think that the Olds rear was more popular than the Ford 9” back then. The work was lone late enough that disc brakes were a thing. Brake lines were run on the axle, but not on the chassis, based on the long lengths of raw brake tubing that was laying inside tha car. This rear has trailing arms that are (from memory) about 40” long and shaped like an inverted U channel. They are mounted to what look like factory clamps welded to the axle and have a couple of rubber. isolation bushings. I suspect it was originally coil sprung in the as- manufactured configuration, but the arms are a lot shorter that the Chevy of the late fifties and sixties, and I don’t see signs of coil mounts. The arms aren’t homemade. I don’t have a good handle of when Olds and Pontiac switched to coils. Again, I think the rear is, to some extent, period correct (except the disc brakes). If parts aren’t available, though, or there’s no easy way to narrow it, the 8.8 is probably the next option.
My olds rear has the same mounting tabs on it. When i look at examples of them in 53 and 54 olds they have sway bars attached there. No idea what the bars you have came out of. I think the olds rear is super cool!
I thought they were the same as these (pictured) you can even see the cut off sway bar end still i the drivers side. Could be yours were modified or just completely different
If you look closely at the third picture, you can see an upper and lower formed plate, each welded to the axle tube. There are rubber bushings between the upper and lower plates, and a couple of bolts holding the trailing arm . the trailing arms are stamped, tapered , inverted U shaped with a pivot on the front end. I am curious as to the original application. Your floor pan is holy, but a lot better than mine!
I see now...yeah man TRUNK floor pan...the rest is a hole not holy.... barely even cross supports haha if yours is as bad as mine we are gonna ned some sheet metal, a bead roller, an english wheel and a tetanus shot!
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