3/4 ton to 1 ton rear end swap

[studeclunker]

I have a '66 C20 Camper Special. My right-rear brake has disintegrated. I was barely able to limp home with it. I also have a '65 C30 with a good rear end on it. The current ratio (Camper Special) is 4/11 (according to the glove box). Would I be able to swap the two?

'65 C30 with 350, 4-speed manual, rear end to:
'66 Camper special 3/4 ton 350 auto 4/11 rear.

Am I nutz?

I tow heavy trailers regularly, so would think the heavier rear end would be an advantage? Also, swapping the rear in off the parts truck would save a week and a lot of money.

[gmc684x4]

There both most likely H072 diff 60 to 72
brakes may differ just have to remember to buy brakes for the other model truck

If it was a k truck you would have to keep matched ratio to front diff

You may gain or lose with a different gear ratio if they both dont match

[gmc684x4]

If drums match just swap brake parts

[burnin oil]

Technically the 3/4 ton should be an Ho52 while the one ton is a ho72. Remove the load bolt and axle shafts and you should be able to pull the chunk out with the gears. The chunks interchange with the only difference being the load bolt on the dually axle. Some ho52s also have the load bolt. My 72 3/4 ton with 4.10s has the load bolt. Theoretically the axle shafts are also the same and the hubs adjust the wheel arrangement from SRW to DRW. If one of the axles has the deteoit no spin it can be moved over to the other gear set easily. The c30 axle probably has 5.14 gears.

I have never tried this but you may be able to use the hubs and drums off the DRW axle on the SRW axle and never switch housings. It may be worth measuring. I recently pulled a ho72 out of a 68 and I needed the leaf springs also for my 57 GMC. I spent 3 days with penetrating oil getting the pins out of the springs since there is no rubber bushings. Its essentially a king pin and they rust really good if not greased reguarly.

[studeclunker]

Originally Posted by gmc684x4

If drums match just swap brake parts

They don't. My C-20 drums are considerably smaller.

Originally Posted by burnin oil

Technically the 3/4 ton should be an Ho52 while the one ton is a ho72. Remove the load bolt and axle shafts and you should be able to pull the chunk out with the gears. The chunks interchange with the only difference being the load bolt on the dually axle. Some ho52s also have the load bolt. My 72 3/4 ton with 4.10s has the load bolt. Theoretically the axle shafts are also the same and the hubs adjust the wheel arrangement from SRW to DRW. If one of the axles has the deteoit no spin it can be moved over to the other gear set easily. The c30 axle probably has 5.14 gears.

I have never tried this but you may be able to use the hubs and drums off the DRW axle on the SRW axle and never switch housings. It may be worth measuring. I recently pulled a ho72 out of a 68 and I needed the leaf springs also for my 57 GMC. I spent 3 days with penetrating oil getting the pins out of the springs since there is no rubber bushings. Its essentially a king pin and they rust really good if not greased reguarly.

Um, I don't quite follow all of this. the one-ton is not set up for duals. Are there markings on the axle housing giving the gear ratio? A tag maybe? Would the backing plates and so on fit the smaller axle?

[burnin oil]

Generally speaking the housings are the same between the 2 axles and the parts are interchangeable. You may be able to take the entire brake assembly including the backing plates off of the donor axle and move them over to the original axle. This would save pulling either axle. You would need to double check the depth of the mounting plate thats welded to the axle that the asking plate bolts too. Also you would have to check the depth of the hub where the tire mounts to it. If these two measurements are the same then the parts should all move over as an assembly. Sorry about the confusion on the duallie rear axle comment. None of my axles have a tag to denote gear ratio. It is stamped on the hogs head as a 2 or 3 letter code that is year specific so basically you would have to count the teeth to be sure. There may be a round tag denoting a Detroit locker, called no spin, on one off the bolts. My truck didn't have the tag but is a Detroit. Factory, unless optioned differently will have 5.14 gears in a one ton and 4.57 gears in a 3/4. 4.10s were an option and were not that common. There is a rumor of some 6 something gears also but I have never seen them. Hopefully this all makes sense.

[gmc684x4]

I looked up yukon gear they listed ho72 for both trucks

My 70 k20 i dug up a dana 60 for rear axle for being more brake upgrade freindly being its not in the line up for shop time i never checked gear ratios

[burnin oil]

It's possible they are both ho72s but I am thinking the lighter axle is a ho52. The trucks capacity should tell us. The 52 is rated at 5200 and the 72 is 7200. They are virtually identical. I am not sure of the date that the ho52 was introduced. Of the OP really wants brakes there is always the 14 bolt dusc swap. Especially if he has the drum brake on the rear if a 4spd trans setup.

[gmc684x4]

I have not seen the 14 bolt disc swap i seen many for dana 60

I did see the gear shop used same diff code as you point out they are internally interchangeable

I have veiwed these diffs as the hated stepchild syndrome as few gear options and very little brake options if any nice to learn of a disc option ic my 60 geared different

[burnin oil]

there is a huge thread on here about the disc swap for the HO52 axle but I bet it works on the HO72 SRW. I have also seen the 3.5" wide 14 bolt drum setup swapped on a SRW. The duallie seems to be the orphan.