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#1
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Chevy 12-bolt identification
I recently picked up a 12-bolt rear and I’m having a hard time decoding the axle tube stamp. The casting number is 3959038 which is a (late) 1969 Chevy 12-bolt. The axle tube is stamped LE 0114K which to me looks like it may be for a 1970 GTO 455 but the LE code doesn’t exist for the 69-70 12-bolt, both for Chevy or Pontiac. Thoughts?
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#2
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Buick? '70 GTO open 2.73 A body McKinnon (Canadian) built 12 bolt
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69 SS/RS 396 M20 X22 Nor 12B,72B,712 bought 1979 FULL OWNER HISTORY 69 Dick Harrell tribute Day II 427 M20 4.10 X11 76 orig pnt, 711 67 Super Stock 302 Camaro re-creation Last edited by bbbentley; 06-13-2018 at 02:19 AM. |
#3
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Yes, the K is for McKinnon (GM of Canada) which is what led me to believe it was a GTO 455 rear since they came with Chevy 12-bolts in 1970. I’ve never seen a factory Chevy 12-bolt in a Buick though.
Last edited by GotGrunt; 06-13-2018 at 01:55 PM. |
#4
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I'm not a Buick expert but here's what Hemmings has to say about 12 bolt Chevy axles in Buick Stage cars in 1970.
https://www.hemmings.com/magazine/1970-Buick-GS-455-Stage-1 What to watch for: GS 455 Stage 1s were automatically equipped with reinforced upper control arms that were not available on the base GS 455. Furthermore, Canadian-built GS 455 and GS 455 Stage 1 cars were furnished with Chevy's 12-bolt differential; however, it featured Buick casting numbers rather than Chevrolet's. A Space-Saver spare became available for the first time.
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...................... John Brown This isn't rocket surgery..... |
#5
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70 Grand Prix 455 also used 12bolt rears.
Is it for sure a 2.73 ratio as Bentley mentioned ? |
#6
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Quote:
It very well may be out of a Grand Prix 455. From what I’ve read, the GTO/GP 455 12-bolt ratios were limited to 3.07, 3.31, & 3.55. The LE code (2.73) listed for the GTO/GP is for the 10-bolt. That is where the confusion is. It is for sure a Chevy 12-bolt and it is definitely stamped LE. |
#7
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If it turns out to actually be 2.73 , then GP
there is a listing for it as 12bolt 2.73 non-posi = LE 12bolt 2.73 Posi = LS 10bolt ratio is 2.78 If it turns out to actually be 3.31 , then Buick A-body LE is basically an "and/or" mystery code according to some Google searches. Did find a few instances of folks trying to decipher ones they had acquired as loose pieces - and the above info is best data found. in case you haven't tried the "turn test" on a non-posi , one revolution with lug stud - count pinion turns - then double that number. 1 and 5/8 approx = 3.31 1 and 1/2 approx = 3.07 1 and 3/8 approx = 2.73 etc ... |
#8
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I had a 69 Buick Special, plain Jane 6 cyl. Made in Canada. It had a 12 bolt Chevy rear. The ONLY difference I could find between this Canadian rear and a Chevelle was the Chevelle casting is 3959038NF, the Canadian did not have NF at the end
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69 SS/RS 396 M20 X22 Nor 12B,72B,712 bought 1979 FULL OWNER HISTORY 69 Dick Harrell tribute Day II 427 M20 4.10 X11 76 orig pnt, 711 67 Super Stock 302 Camaro re-creation Last edited by bbbentley; 06-13-2018 at 12:09 PM. |
#9
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Quote:
It’s funny you mention that because this casting doesn’t seem to have the N or NF at the end either. I will double check that though once I get it out of the car and thoroughly clean off the housing. I wonder if all the McKinnon/Canadian Chevy 12-bolts were this way. |
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