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Rod · 04-09-2005, 09:47 PM

Looking at the GM parts book it lists a part # of 1970 rear axle as 3966276 says its the same as 71-72 4wd rear axle..and there 6 bolt ...so might ask for a 71-72 rear 4x4 axle ...and you might get the correct one.

I'll add a little here for the 2wd guys thinking about swap to 71 - 72 axles.

That 70 rear axle is the odd lot...in some cases a 70 rear axle will take a 71-72 5 bolt rear axle...for 2wd applications. It's a swap to 5 bolt pattern that makes this year of diff somewhat sought after as it can be swapped between 5 and 6 bolt axles from stock trucks. I have had a 70 that didn't allow the 5 bolt axle..it was a little longer about 3/4 inch...so I think it might be a change over period where some fit some dont. The typical 71-72 axle is about 3/4 inch longer than the 6 bolt pattern 67- 69 -70ish.

04-09-2005, 09:47 PM	#2
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	Looking at the GM parts book it lists a part # of 1970 rear axle as 3966276 says its the same as 71-72 4wd rear axle..and there 6 bolt ...so might ask for a 71-72 rear 4x4 axle ...and you might get the correct one. I'll add a little here for the 2wd guys thinking about swap to 71 - 72 axles. That 70 rear axle is the odd lot...in some cases a 70 rear axle will take a 71-72 5 bolt rear axle...for 2wd applications. It's a swap to 5 bolt pattern that makes this year of diff somewhat sought after as it can be swapped between 5 and 6 bolt axles from stock trucks. I have had a 70 that didn't allow the 5 bolt axle..it was a little longer about 3/4 inch...so I think it might be a change over period where some fit some dont. The typical 71-72 axle is about 3/4 inch longer than the 6 bolt pattern 67- 69 -70ish. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.