I got my car in the air and got these numbers off of the 12 bolt. Can someone tell me if this rear is correct for this car "GM51" "3969278NF" 1970 GS 455 Skylark.
Skylark GS models did not come with 12 bolt rears. Look at your cowl tag and see if it says MADE IN CANADA at the bottom. If so, Canadian built GS models got the Chevy 12 bolt. Otherwise, someone swapped out the original 10 bolt 8.2" rear.
Gary, As far as I know and I think Duane Heckman will agree, no US made Skylarks had 12 bolt Chevy rears from the factory. Would love to see some documentation on factory 12 bolt installation. I have gone through 150+ Skylarks in the last 20 years of yarding and never found a 12 bolt in any of them except Canadian built models.
Have to agree with Iceman, as I've pulled an original out of a '70 2 door post car & two more out of 2 door hardtop '70 Skylarks. All were just normal 350 Skylarks, & the rears dated the cars. These 12 bolts were same casting # as used in '70 455 GP & GTO, not the Chevelle date coded in the webbing version. :3gears: Roger
Roger, Those were US made cars??? Only way to ID Canadian cars is the "MADE IN CANADA" cowl tag. Did you check the cowl tag on any of them? Also, you need to clear your PM box.
George, Yes these were all Framingham built Skylarks as I ck'ed the cowl tags. The postcar has been processed & crushed, but the two '70 hardtops, I pulled the rears from, are still sitting in one of my favorite yards. Will get the body build date info next time I'm down that way. Roger
George-Duane does know a lot, but I don't think anybody knows eveything about these cars, especially oddball stuff like what were dealing with here. You probaly wont find this info. in any book or assembly manual. For whatever reason, some of the 70 Skylarks from the U.S. Framingham plant ONLY had 12 bolts installed in them. Why? Maybe to keep the line moving? IMHO, the only people that know why are the people that were working there at that time, and since thats been 35 years ago, it would not surprise me if we never knew why. How many were installed? Thats probaly another question thats impossible to answer. I do believe it was not very many. I've only ever found one in all the years I've been going to the junkyards.
Roger-I wiil post the info. from the Framingham built 12 bolt Skylark I found if you want to compare it to the info. you get from the ones you found. The VIN is: 435370G130019. Cowl tag info: the unit # is:67850. And the time built code is: 03B, which I believe translates into the second week of March, 1970. I'm 99.9% positive it was the original rear end. I bought the rear end a few years ago for 100 dollars and didn't have a clue as to how rare it was. The last time I went to that yard I made sure I got the VIN and pulled off the cowl tag just in case it gets crushed, as its nothing but a rusted out hulk now. I tried to find the build sheet, but it was rotted away. Later
12 bolt rear end Good morning , I bought my 1972 GS Stage 1 in Saint John New Brunswick Canada .It was built in Framingham Mass. October 21, 1971 and it came with a Chevrolet 12 bolt 3.42 ratio from the factory. I put a set of 3.73 gears in it that year out of a friends 1970 LS6 Chevelle. The rear ends were identicle and mine still has the same rear end only with 3'08s. The 12 bolts were in Canadian built cars and american built ones for Canada. Bill
Just wondering, why would the Canadian GS's come with a heavier duty rear end?(12 bolt) It's not like the car is going to "hook" harder in all the snow up here. :laugh: Jim
