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**1project2many** · 10-29-2015, 02:17 PM

56james, that is an original type axle. It is not generally called a "ten bolt." There are stamped and cast codes that can be used to determine the age of the axle. Here is the 1955 truck manual section for the rear diff:
http://chevy.oldcarmanualproject.com...55ctsm0401.htm

joedoh, the 8.2 ten bolt came out around 64-65. The terms "ten bolt" and "twelve bolt" were coined to identify whether an axle was a stock "low performance" part or an optional hi-po diff. The 8.2" ring and pinion must be removed from the back of the housing, just like the later 8.5" rear. An original 8.2" cover will usually interchange with the 8.5" cover. Most can be quickly identified by the oil channels stamped into it.

FWIW, this only applies to Chevrolet designed axles. B,O,P, and Caddy did some very different stuff, like putting 12 bolt rear covers on 8.3" axles, using cone style posis, and building a heavy duty 9 3/8" ring gear axle.

Here's a page that can help id some of the GM axles:
http://www.crankshaftcoalition.com/w...identification

And here's a good article on the history of 10 and 12 bolt axles:
http://www.chevydiy.com/history-and-...differentials/

10-29-2015, 02:17 PM	#4
1project2many Senior Member Join Date: Mar 2012 Location: Lakes Region NH Posts: 3,217	Re: Help me ID my rear 56james, that is an original type axle. It is not generally called a "ten bolt." There are stamped and cast codes that can be used to determine the age of the axle. Here is the 1955 truck manual section for the rear diff: http://chevy.oldcarmanualproject.com...55ctsm0401.htm joedoh, the 8.2 ten bolt came out around 64-65. The terms "ten bolt" and "twelve bolt" were coined to identify whether an axle was a stock "low performance" part or an optional hi-po diff. The 8.2" ring and pinion must be removed from the back of the housing, just like the later 8.5" rear. An original 8.2" cover will usually interchange with the 8.5" cover. Most can be quickly identified by the oil channels stamped into it. FWIW, this only applies to Chevrolet designed axles. B,O,P, and Caddy did some very different stuff, like putting 12 bolt rear covers on 8.3" axles, using cone style posis, and building a heavy duty 9 3/8" ring gear axle. Here's a page that can help id some of the GM axles: http://www.crankshaftcoalition.com/w...identification And here's a good article on the history of 10 and 12 bolt axles: http://www.chevydiy.com/history-and-...differentials/ Last edited by 1project2many; 10-29-2015 at 02:29 PM.