Another C20 rear end question - New member

[customc20]

Hello everyone. I am new to this site (First post). The wealth of knowledge here is amazing. I recently inherited my 1972 C20 Custom Camper from my grandfather who passed away. My wish list for this truck is growing by the day. I think I'm going to start with the brakes/suspension and move from there. The truck is a 3/4 ton with coil rear suspension and an HO52 rear end with 4.10/4.11 gears. It has an unmodified 350 with a TH350 tranny. It has front discs and rear drums.

I have searched this site extensively for rear end conversions and I think I know which way I would like to go. I want to end up with a slightly built up 350 with a 700R4 tranny and a 3.73 POSI in the rear running around ~28-29" tires on ~20" rims. I'll do a 4/6 drop while modifying the suspension. I would like to switch to 5 lugs all around for the rim choice. I will not be towing anything with this truck. I will also switch to disc rears with the rear end coversion.

Since I have an HO52 rear end I know I'm already at the best gear I can get in that housing (4.11). I know there is/was talk of a 3.90 aftermarket gear available, however, I would like to have a POSI (not a locker) so this is pushing me to replacing it with something else. I have been eyeing the newer C10 axles from 73+ however, I can not locate one locally. Has anyone tried to put in a rear end from something from the 90's? I know I will have to weld the perch's and panhard/trac bar mount to the axle tube hosing, so this is not a consideration. I would be open to buying the rear end, then buying aftermarket POSI center section, however, I would rather buy it all together. Like I said, I'd like to end up with 5 lugs, so whether the new axle already has that setup, or a conversion axle needs used, I'd like to end up with this. I know the width of the newer rear ends are probably a little wider, so this is why I'm asking. Can some one point me in the right direction for a new rearend? Please be specific on models and years of your suggestions. I've read all the rear disc conversion setups (and associated aftermarket sites) so I think I'll be able to find something to fit.


Sorry to ramble on, however, I wanted to give as much information as possible so I can receive useful feedback. Again, I've searched hundreds of posts regarding this conversion, but can't quite identify exact years of newer rear ends to use.

Thanks for your help!

Mike

[gcburdic]

anyone able to help Mike out....BTW to the boards from NC

[treveiger]

Why the newer rear ends? Welcome to the forum!
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[customc20]

Thanks for the welcomes. I am having trouble locating an older rear end. (72-87) The newer styles (90's) are much more abundant. I'm not opposed to an older rear end, I just need help locating one. I'll post a request on the WTB section. Since I want a 3.73 posi, and the posi's seem to be more abundant in the newer rear ends.

Has anyone replaced they're rear end with an 88+ chevy rear end?

Or does anyone know/have one they'd like to sell?

[gcburdic]

hey Mike....have you tried looking on your local craigslist...that'd be where I start looking...someone may be parting a 67-72 truck that has what you are looking for, but the 67-72 with posi are getting harder to find, but you could go with a PowerTrax type setup too....

Also, since you are new around here, just wanted to remind ya that you'll need to be a subscribing member to ask for WTB stuff....click here for more info or let me know if I can help you out....

[customc20]

Thanks Geoff for the heads up on the subscribing member details. I'll do that right away.

I visited PowerTrax's website (Richmond Gear) and they don't list a solution for the HO52 rear end for a 72. Am I missing something, or can the 73-87 powertrax fit in? This could be a good solution rather than swapping the whole rearend.

Anyone have any experience putting one of these in an HO52?

[Mercury694]

I don't have answers, but I have a similar problem and am interested in what you find out. I've got a 68 c20, with 456(?)ish rear end. At 50 mph, I'm turning over 3k rpm in 4th gear (with no slipping at the clutch). I'd like to keep my 8 lug setup and go way up to a gear in the 3.3-3.6:1 range. I know that's a long jump, but even with 2 ton in the bed I don't need first gear and my commute is largely highway. I am also not against doing a little machining or welding in order to install it. I'm talking to a local differential guy, and he's looking into options but I thought I'd see if anyone here was dealing with similar issues or had an idea on how to progress. I am not against custom made, but my wallet is.

[gcburdic]

Originally Posted by customc20

Thanks Geoff for the heads up on the subscribing member details. I'll do that right away.

I visited PowerTrax's website (Richmond Gear) and they don't list a solution for the HO52 rear end for a 72. Am I missing something, or can the 73-87 powertrax fit in? This could be a good solution rather than swapping the whole rearend.

Anyone have any experience putting one of these in an HO52?

I'm not sure on the HO52...I was thinking 1/2 ton truck...sorry....hopefully someone can assist here

[Mercury694]

After talking to a few people, many of the rear diffs from the newer Ford diesels have a 3.73 ratio. It would still likely be an 8 lug w/drum, which may work for me but not for you. I gotta figure out if the bolt pattern is the same, I think I can take a rim down to the boneyard and determine that and make sure the width works out. I'm also looking into half ton diffs, but I don't really want to go 5 or 6 lug. Maybe 3.73 and taller tires would be a better way to go.

[factorystock]

It is strange that Chevy never offered a 3.73 ratio for 3/4 ton axles between 67 and 72. No need to "de truck" the vehicle (reducing its carrying ability).The easiest swap would be a Dana 60 8 lug with 3.54's straight out of a big block 68 thru 72 C20 or burb with coil set up.Get the panhard bar also.It does require some leg work to find though.

[customc20]

Are the dana 60's posis or lockers? I really dont want a locker since I do street driving all the time. Are there aftermarket posi/limited slips carriers for the dana 60?
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[Stricklinator]

Originally Posted by customc20

Are the dana 60's posis or lockers? I really dont want a locker since I do street driving all the time. Are there aftermarket posi/limited slips carriers for the dana 60?
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They make just about everything for a Dana 60; it's a very popular unit for 3/4 ton trucks and a popular swap for off road/rock crawling vehicles.
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