I have 2 uppers that are shaped differently from one another. Is there a right and a left? I don't see any stampings on them and can't really see the difference between them except on the ends that attach to the rear end. One of them has got an angled cut at the end that the other one does not. These are genuine GM parts that I removed the tags from to repaint. Here's a couple pics........
Thanks for the reply Larry, these are off of a 12 bolt FWIW. They both had the same part# labels on them. 9798994
...likely an "after-the-fact" mod, can't imagine OEM with so little metal at bolt hole. Only other thing I can think of is possibly piece was cut at edge of steel sheet, should have been rejected by QC. I'd replace it...
That is a correct arm for a 12 bolt rear !! One side was clipped at corner to clear a casting bump on pumpkin . If u look inside there should be a reinforcing washer welded in from factory ! You’re not crazy , factory did this , but only had to do so on 12 bolts !!!!
12 bolts which were found in Canadian built GS and a bunch of 70 skylarks and GS’s built in Framingham mass plant ! I’ve owned 3 and prob seen another 6 out of framingham with the 12 bolt !!
More detailed info: https://www.lever-family-racing.com...-2/gm-a-body-64-72/10-bolt-12-bolt-difference https://www.lever-family-racing.com...0-bolt-12-bolt-difference/create-12-bolt-arms
Yep . Clearance issues. I noticed that installing my 12 bolt. I had to buy a kit to get my arms beefer. From switching over. After MIG welding a few small plates on the uppers. I had to take some off the driver side arm for clearance. 1/4 inch or so.
Wonder if that Arm Nick has was the ones Buick put on the Canadian 350 Buick special ( Skylarks) That had 12 bolts in them .
Mine came off a 1968 Canadian Skygoose with 12 bolt. Both are radiused, and one has the square reinforcement shim, but otherwise, they are identical to each other.
The ones that I have came off my buddies '67 GTO that had a 12 bolt in it that he gave to me and will be going in my GS. I know that they were bought new with the boxed lowers from a GM dealer back in 1980-81 as a complete 4pc set along with the factory sway bar.
Very nice Nick Beautiful. Yes mine was out of a 70 Judge. Loaded my rear end with Timkin Bearings. Never look back
Looking in the '71 parts manual I find that there are many different part numbers for the arms (upper & lower) depending on the rear,year, Transmission, wagon, tow pkg, etc. I'll try to post the page here.
