72 C20 14 bolt gear swap

[Bisblue]

Just bought this 72 for 1200 bucks. It's got a 292, that runs decent and a Muncie granny 4 speed.

It needs lots of love, but mainly it needs, higher gears. I think it has 4.11 or 4.56 gears, so it's howling at 55 mph.

I've read lots of threads on axle swaps, I want to keep an 8 lug rear since it has disc breaks, power steering and handles great. I was hoping to build a small block and make it a cruiser down the road, with a work truck vibe. I like the current stance and just need to lower the rear an inch or two to level it out, so no drop spindles or anything like that planned.

Has anyone swapped a more modern 14 bolt into a C20, I've read that some of the newer axles are a little wider and I'd love some advice. I haven't seen many older axles at the junkyards here in Vegas and was hoping to find something with high gears like 3.08 or 3.42s, but 3.73s would work if it's all I can find.

[cooperhw]

Originally Posted by Bisblue

Just bought this 72 for 1200 bucks. It's got a 292, that runs decent and a Muncie granny 4 speed.

It needs lots of love, but mainly it needs, higher gears. I think it has 4.11 or 4.56 gears, so it's howling at 55 mph.

I've read lots of threads on axle swaps, I want to keep an 8 lug rear since it has disc breaks, power steering and handles great. I was hoping to build a small block and make it a cruiser down the road, with a work truck vibe. I like the current stance and just need to lower the rear an inch or two to level it out, so no drop spindles or anything like that planned.

Has anyone swapped a more modern 14 bolt into a C20, I've read that some of the newer axles are a little wider and I'd love some advice. I haven't seen many older axles at the junkyards here in Vegas and was hoping to find something with high gears like 3.08 or 3.42s, but 3.73s would work if it's all I can find.

Yes. I swapped the entire rearend on my 68 last year (build name "Meet Homer") with a 79 rearend. mine was a dually, but still the same swap. Easy peasy. Look up my build thread, lots of pictures. I bought a whole chassis and swapped both the front and rear ends by myself. No sweat.

[Bisblue]

Thanks wayne,
My only problem is finding older axles, I was wondering about the newer 90s and 00s rat ends for fitment.

[Bisblue]

On a positive note, I found this under the funky gray paint job.

[bigdog55]

I talked to a guy about a year ago about changing the rear end.He had changed the rear end out with a 2002 (i think-- I just r ember it having disk brakes ) I'm sure there would be a little modification

[ElKotze]

On my '69 Longhorn I switched in a 14-Bolt semi-floater out of a '82 3/4-ton. I had to move the spring perches and shock mounts, not a big deal if you have an angle grinder and a welder. There are all kinds of different gears out there for that axle, I put 3.42's in. The 14-Bolt full-floater is the better axle for heavy hauling and off-roading, but not by much. Plus, on those newer axles you don't have to pull the axle to get to the drum brakes. Yes, they are a little wider and the tire moves out a little, more like on a late model truck. And, I didn't have to use a conversion u-joint, takes the same.

[cooperhw]

Originally Posted by Bisblue

On a positive note, I found this under the funky gray paint job.

Nice.

[Mike C]

You don't say, but is your GMC leaf? Most are but coils were a no cost option. I have a 69 Chevy short step 1/2 ton that's leaf and a 71 GMC 1/2 ton longbed right behind it in the driveway that is coil.

The reason being is a leaf spring swap is fewer brackets and less cutting and grinding than a coil spring setup. If you have 42.5" spring center (4x4 and Longhorn and C30 are 40.5") then a 73+ 3/4 ton has perches in the right place just need to relocate the shock mounts. A 73+ one ton has the 40.5" perches FWIW.

Another donor consideration is the semi-float 14 bolt. I have an 8 lug one in my Jimmy that was not a first choice but has turned out to be an excellent swap. And they are relatively cheap and 3.73 are really common as well and I think 3.42 are out there.

[Bisblue]

Thanks for the heads up,
Mine is a leaf spring. I'd love to find an older axle, but if I have to move the perches no worries. It just seems like 90s and up axles are a dime a dozen here in Vegas.

[Mike C]

Remember that Suburbans ran until '91. Like me, I think you would find the semi-float 14 bolt from a Sub to be a great swap.

[Bisblue]

Thanks Mike,

Yeah I'm not planning on towing or hauling, but just want a cool work truck/ daily driver. I've got a cummins for towing.

I just have a great riding truck now and don't want to have to do a front end swap to get ps and pb since I have them now. I think a semi floater would be fine for me.

Adam

[Mike C]

The 9.5" 14 bolt is rated up to 8600# GVWR on some vehicles so it's load capacity is beyond anything the 67-72 C20 were rated for. Even if you wanted to tow heavy, it's equal to the rest of your truck.