1970 LT-1 Rear Gear

[Bob H.]

My car has a date correct rear that is the 3:55 CAZ. In some books it refers to this as heavy duty posi for 454. Other docs just say it a heavy duty posi.

Could the LT-1 have the CAZ heavy duty 3:55? Thanks

[Joe L.]

Re: 1970 LT-1 Rear Gear

My car has a date correct rear that is the 3:55 CAZ. In some books it refers to this as heavy duty posi for 454. Other docs just say it a heavy duty posi.

Could the LT-1 have the CAZ heavy duty 3:55? Thanks

Bob------


GM used "HD" to denote Corvette rear gear units which were equipped with cap type stub axles. All big block got the "HD" type. Some small blocks did, too, including most, if not all, LT-1. I've even seen some base engines that were equipped with known original HD rear units.

[Gary R.]

Re: 1970 LT-1 Rear Gear

yeah, it has been kind of deceiving calling the diff HD when in fact many of the so-called HD diff's broke as much as the standard ones. By the 70's they were going down in QC. The posi cases were better from 72-79 than the previous ones but other areas that failed were clutches, axles, and ring gear bolts.
My original 1972 base engine TH400, ac car has a "HD" differential.

[Bob H.]

Re: 1970 LT-1 Rear Gear

Thank you guys!