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I have a 54 3100 with a 56 rear end from a donor truck under it. The rear end looks like a regular chevy 10 bolt. I would like to change the gears from 4.11 to 3.42. Could some one tell me which years/type of gears would fit in this rear end. Thanks for any help.

It depends on the 10 bolt. GM made a bunch of different types of 10 bolt rear ends over the years.

First thing to do would be an inspection of the rear axle shafts, bearings,& spider gears. If your axles are twisted or worn, then you'll have to figure in the cost of new parts to the gear swap. If you're gonna dump any serious power into the rear end, you may want to replace those 46 year old axleshafts anyway.

For the gear swap: Get the numbers off the axle tube, and verify its a '56 rear end. Next, figure out what diameter ring gear you need, as different 10 bolts had different dia ring gears. Also find out if the carrier you have will fit a 3:42 gearset, as some GM 10 bolts used a carrier for numerically "high" gears and another carrier for numerically "low" gears.

There are guys who are more familiar with the '56 truck rear ends. They can tell you where the ID numbers are on the axle tubes, and the specs on the carrier. Guys??

hope this helps

chiphead