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raycow · 11-04-2010, 08:17 AM

You have the stock 1/2 ton rear which was basically the same from 55 to 62. GM's designation for it was H033. Some aftermarket vendors call it a 55T. Others call it an Eaton, which is incorrect, because it was always made by GM.

It is a very tough, strong rear, and has no real problems apart from limited gearing choices and parts availability. You can still get bearings, seals and gaskets, but not a whole lot else. Fortunately, the spider pin appears to be the same as used in the later 12 bolt rear.
http://www.ringpinion.com/PartsList....fID=37&CatID=9

The 17 spline 8.5" rear you found was used in Chevy cars, and very little from that will interchange with the truck rear.

Btw, if you have problems with excessive shaft end play, the cheap fix is to install a new spacer block wide enough to take up the extra clearance. GM used to sell these in a couple of different sizes, but they haven't been available for quite a long time. It is a very easy job for any machine shop to make one.

Ray

11-04-2010, 08:17 AM	#4
raycow Registered User Join Date: Mar 2003 Location: San Francisco, CA USA Posts: 2,454	Re: help with rear end identification You have the stock 1/2 ton rear which was basically the same from 55 to 62. GM's designation for it was H033. Some aftermarket vendors call it a 55T. Others call it an Eaton, which is incorrect, because it was always made by GM. It is a very tough, strong rear, and has no real problems apart from limited gearing choices and parts availability. You can still get bearings, seals and gaskets, but not a whole lot else. Fortunately, the spider pin appears to be the same as used in the later 12 bolt rear. http://www.ringpinion.com/PartsList....fID=37&CatID=9 The 17 spline 8.5" rear you found was used in Chevy cars, and very little from that will interchange with the truck rear. Btw, if you have problems with excessive shaft end play, the cheap fix is to install a new spacer block wide enough to take up the extra clearance. GM used to sell these in a couple of different sizes, but they haven't been available for quite a long time. It is a very easy job for any machine shop to make one. Ray __________________ Live more responsibly. Eat lower on the food chain. Eat vegetarians. Last edited by raycow; 11-04-2010 at 08:28 AM.