So, this car has been off the road since the early 80's, i had found peices of the build sheet under the rear seat, it decoded to a 400 2-BBL, 3-Speed Manual, 12-bolt, Sport.
on PY forum they swear up and down there is no way a 400 car, let alone a LeMans came with a 12-bolt...
but there is a Chev style 12-bolt under the car? factory or not?
Car is a Canadian built car.
-- Edited by 455LemanSport on Saturday 27th of April 2013 01:34:44 AM
Yes, I just went and checked the GM of Canada parts book for Lemans. 70-72 A body lists a 12 bolt. If they still don't believe you, tell them you will post proof and I will scan the page in the book.
It doesn't mention 69 so maybe in Lemans it only started in 70. I know Cutlass and Skylark started earlier, I think 68. Years ago, my brother had a Canadian 69 Cutlass 2 door hardtop, 6 cylinder, power windows and a 12 bolt! Strange combination.
-- Edited by Carl Stevenson on Saturday 27th of April 2013 08:42:21 AM
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
Why don't you cut that old odd ball rear end out, and let me ease the pain with $1500.00 cash and I will pay to have it shipped to Ont get rid of it ()
-- Edited by 427carl on Sunday 28th of April 2013 07:51:38 AM
I believe you are correct. The Canadian A body Olds, Pontiac and Buicks had 12 bolts in at least 69 and 70, and I believe they are correct for the US cars.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
Mine too ! I love GM Canadian built cars something do be proud of ... 1972 Pontiac Luxury Lemans Sport Coupe with 400 4 barrel and the famous 12 bolt 3.31. 1970-72 Pontiac Lemans/GTO 455 powered USA cars got the 12 bolt ...
Mine too ! I love GM Canadian built cars something do be proud of ... 1972 Pontiac Luxury Lemans Sport Coupe with 400 4 barrel and the famous 12 bolt 3.31. 1970-72 Pontiac Lemans/GTO 455 powered USA cars got the 12 bolt ...
yup...that's one of the ways to tell a real 455 GTO...
that and the super side motor mount
( useless knowledge..;)
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later...rog
AADD supporting member !!
I'm a collector...not a builder!!Located in sunny central Saskatchewan at the lakehead!
The U.S. version of that car would have come with an 8.5" 10-bolt rear. I think at that point the lesser cars (350 & less) may have still been using the 8.2" 10-bolt.
Hey, if the guys insist the Canadian & U.S. Lemans are the same, why dont you ask them which 350s were available in Canada?
The 12-bolt normally was used on the 455 cars, but I would expect them to be also used on the 400 cars in Canada rather than the 8.5" 10-bolt that the U.S. cars got.
I bought a 69 all original Nova, non SS, from California and found it had an open 12 bolt, 3:07 differential when I strapped it down on my trailer. Research showed 166 (I think) built and the 12 bolt came as an option called, Heavy Duty Rearend. It was intended for someone wanting to tow not performance.
Canadian built and sold 1970 400 GTOs have the 10 bolt (the 8.2" BOP 10 bolt, not the 8.5" 10- bolt, last year for this axle. 71 up got the 8.5) I also know of a 330hp 4 speed Lemans and it has the BOP 10 bolt. Is the 12 bolt in your car 3.55 ratio? If it is it's more odd yet, 3.55 was the special order perforamce ratio, 3.31 or 3.07 with AC was standard. The service manual lists the 4-pinion HD version of the BOP axle for all 400 4-speed applications in 1970, with 3.55 the standard ratio without AC. So is it possible that a "455 only" 3.55 12 bolt assembly was substituted for the "400 only" 3.55 HD 4 pinion 10 bolt? It is well known (at least North of the 49) that Oshawa used lot's of 12 bolts in places the US plants didn't as some other posters have pointed out, but this practice seems to have ended in the 69/70 changeover, for the same reasons (changes to the auto pact that let part cross the order without tax) that Beaumont production was halted and Pontiac A-bodies started at Oshawa. All that said any 400 - 4 speed drive line is pretty uncommon in a 70 Lemans Sport so it's not like I (or anybody else) can say that they've seen lots of others. If there was a car that was going to get a "not supposed to be" drive line in 1970 it would be a big engine, 4 speed, Canadian market, non-GTO.
I guess what I'm trying to say is that having had a lot of these cars I am remaining politely skeptical unless lots of other details match. What's the casting date on the axle? Does it fall in the window for the build date of your car? What U joints are used? (Size and P/N for the Pontiac 12 bolt are different from the Chevy one).
Stu
-- Edited by Evil Stu on Thursday 23rd of May 2013 07:22:33 AM
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Having a 10 second import is like coming out of the closet. It will surprise a lot of people but you'll still be gay.
I have taken more chevy 12 bolt diffs out of 68 and 69 skylark and cutlass cars than ay other,but have taken quite a few out of 70 lemans cars as well 2 and 4 dr. cars-all in Canada.So unless there was someone out there swapping these into Canadian cars before they went to the wreckers-they were stock diffs when built in Canada.I have a 68 Skylark 4 dr. hardtyop right now that has a chevy 12 bolt in it
its true....