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brontotx · 02-11-2012, 12:03 PM

I'm a little late to the discussion, but another option is to use the early 14 bolt full floater (8 lug) and the bolt-on adapter plates discussed here (scroll down a ways) and available at www.rightgear.com (note: their website does not show this product). These plates adapt the 2002 and later 2500 HD disk brakes to the early 14 bolt single rear wheel axles and maintain the 67" wheel mounting surface to wheel mounting surface width of these axles, which I believe is what was in the earlier C20s (I have an '82/5 C20 and it is a direct bolt in). Compared to other disk conversions for these axles, the 2500 HD disks feature two pistons and a cable-actuated "drum in a hat" emergency/parking brake.

I've got all the parts and am in the process of performing this conversion. I bought a complete used 14 bolt full floater single rear wheel axle for $200, a lightly used (80k miles) 14 bolt from a 2004 2500 HD for $300, and the adapter plates from right gear for $265 (including shipping). Since I also switched the 4.10 ring and pinion to 3.73s, installed new bearings and seals, and put in a lightly used posi, it is not as "budget" as I would have liked, but it should be stout and trouble-free for a long time. While I could have gotten just the 2500 HD brakes, the conversion uses a lot of the brake-related parts (including the hoses, lines, and shields), so getting the whole axle seemed cost-effective in the long run - besides, I should be able to sell the left over axle housing with gears, axles and hubs. I'll post some pics later.

As someone else noted, the width of the later axles is a tad over 68", meaning the wheels will mount about 1/2 to 3/4 of an inch wider on each side compared to stock if you go this route, which shouldn't be a problem for our trucks. Of course, you'll need to cut the spring perches and shock mounts off the later axle and weld new ones on in the correct locations.

In regard to towing/hauling with a 700R4, I bought my C20 in '97 and it had a lot of miles then. I towed/hauled regularly (not professionally) as a weekend DIY warrior and the original "weak series one" 700R4 finally died about 5 years ago. I replaced it with a later 700R4 specifically designed and built for towing/hauling (the "Heavy Hauler" from Performabuilt Transmission) - it has been troublefree ever since.

02-11-2012, 12:03 PM	#6
brontotx Registered User Join Date: May 2009 Location: Space City! (TX) Posts: 46	Re: 1972 C20 Rear Axle Swap I'm a little late to the discussion, but another option is to use the early 14 bolt full floater (8 lug) and the bolt-on adapter plates discussed here (scroll down a ways) and available at www.rightgear.com (note: their website does not show this product). These plates adapt the 2002 and later 2500 HD disk brakes to the early 14 bolt single rear wheel axles and maintain the 67" wheel mounting surface to wheel mounting surface width of these axles, which I believe is what was in the earlier C20s (I have an '82/5 C20 and it is a direct bolt in). Compared to other disk conversions for these axles, the 2500 HD disks feature two pistons and a cable-actuated "drum in a hat" emergency/parking brake. I've got all the parts and am in the process of performing this conversion. I bought a complete used 14 bolt full floater single rear wheel axle for $200, a lightly used (80k miles) 14 bolt from a 2004 2500 HD for $300, and the adapter plates from right gear for $265 (including shipping). Since I also switched the 4.10 ring and pinion to 3.73s, installed new bearings and seals, and put in a lightly used posi, it is not as "budget" as I would have liked, but it should be stout and trouble-free for a long time. While I could have gotten just the 2500 HD brakes, the conversion uses a lot of the brake-related parts (including the hoses, lines, and shields), so getting the whole axle seemed cost-effective in the long run - besides, I should be able to sell the left over axle housing with gears, axles and hubs. I'll post some pics later. As someone else noted, the width of the later axles is a tad over 68", meaning the wheels will mount about 1/2 to 3/4 of an inch wider on each side compared to stock if you go this route, which shouldn't be a problem for our trucks. Of course, you'll need to cut the spring perches and shock mounts off the later axle and weld new ones on in the correct locations. In regard to towing/hauling with a 700R4, I bought my C20 in '97 and it had a lot of miles then. I towed/hauled regularly (not professionally) as a weekend DIY warrior and the original "weak series one" 700R4 finally died about 5 years ago. I replaced it with a later 700R4 specifically designed and built for towing/hauling (the "Heavy Hauler" from Performabuilt Transmission) - it has been troublefree ever since. Last edited by brontotx; 02-11-2012 at 12:09 PM.