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 ()

my 72 Lemans Sport with 400 4-speed came with a factory twelve bolt and boxed control arms

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 ... 

455LemanSport wrote:

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Thought so! thanks guys!

when i mentioned that it was a Canadian car, they said Canadian cars are identical to the US ones!

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 The best advice I can give you is to ignore the other forum and stay here. You are among friends and people who know what they are talking about here.

I'd pay good money for that original soft bend stabilizer bar.

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.

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