Toying with the idea of C30 to K30 conversion

[JJorgensen52]

Gents,

I'm toying with the idea of doing a 4x4 conversion on my '72 GMC. It gets used for hauling firewood out back and other things for which it would be useful.


So, that said, looking for input or info from anybody who's done this before. I've done some searching and I've come up with not a whole lot.

I also have a slight dilemma in that this truck has a PTO driven hydraulic bed setup and I'd like to not have to completely rework everything to move it to clear the transfer case.

With all this in mind, I've come up with this:
-78+ SM465 (32 spline output 4wd with NP208 transfer case adapter)
-BW4401 or BW4470 1 ton transfer case from a 87-00 K3500
-D60 driver's side pumpkin - this would come from a Ford 1 ton and swap the knuckles/brakes to Chevy parts

As far as the front springs go, I'd probably use 3/4T rear springs, and make custom hangars so I don't have to drill through the frame. This would also give me a bit of a front end lift.

I'd probably then add some blocks in the rear, or possibly flip the hangars and add longer shackles, to keep it level.

Obviously I need custom drive shafts for this. The rear I should just be able to shorten the mid-shaft.

I don't see any particular reason to swap my engine cross member, as all the front end components are bolted to it and can be removed. If I need to, I'd probably use one from a K20.

I understand it'll be a bit of work, but this seems doable to me. Am I crazy or not? Comments / advice appreciated!

[mx289]

Do it.!I like all your ideas and you know what your in for.I have seen a couple done on this forum.I just bought a 71 c30 and have been thinking about doing the same conversion as well,but one project is enough!I will be watching yours for sure.

[BLAZERMAN]

Originally Posted by JJorgensen52

Gents,

I'm toying with the idea of doing a 4x4 conversion on my '72 GMC. It gets used for hauling firewood out back and other things for which it would be useful.


So, that said, looking for input or info from anybody who's done this before. I've done some searching and I've come up with not a whole lot.

I also have a slight dilemma in that this truck has a PTO driven hydraulic bed setup and I'd like to not have to completely rework everything to move it to clear the transfer case.

With all this in mind, I've come up with this:
-78+ SM465 (32 spline output 4wd with NP208 transfer case adapter)
-BW4401 or BW4470 1 ton transfer case from a 87-00 K3500
-D60 driver's side pumpkin - this would come from a Ford 1 ton and swap the knuckles/brakes to Chevy parts

As far as the front springs go, I'd probably use 3/4T rear springs, and make custom hangars so I don't have to drill through the frame. This would also give me a bit of a front end lift.

I'd probably then add some blocks in the rear, or possibly flip the hangars and add longer shackles, to keep it level.

Obviously I need custom drive shafts for this. The rear I should just be able to shorten the mid-shaft.

I don't see any particular reason to swap my engine cross member, as all the front end components are bolted to it and can be removed. If I need to, I'd probably use one from a K20.

I understand it'll be a bit of work, but this seems doable to me. Am I crazy or not? Comments / advice appreciated!

I've been accumulating parts for a few years to do this same conversion. As far as your front crossmember I would ditch it in favor of a stock 4x4 engine cradle, you will have much better clearance over your axle with the smaller 4x4 cradle than the 2 wheel drive version. And for a transmission why don't you just leave your SM465 you have now since it already has your PTO setup for the pump...just use a divorced Dodge NP205 from a mid 70s truck, it's a passenger side drop so you can use the GM Dana 60 front axle and you should have plenty of length for the divorced case with your longer wheelbase. Either way you do it should be a really cool project.

[JJorgensen52]

Originally Posted by BLAZERMAN

I've been accumulating parts for a few years to do this same conversion. As far as your front crossmember I would ditch it in favor of a stock 4x4 engine cradle, you will have much better clearance over your axle with the smaller 4x4 cradle than the 2 wheel drive version. And for a transmission why don't you just leave your SM465 you have now since it already has your PTO setup for the pump...just use a divorced Dodge NP205 from a mid 70s truck, it's a passenger side drop so you can use the GM Dana 60 front axle and you should have plenty of length for the divorced case with your longer wheelbase. Either way you do it should be a really cool project.

That makes good sense on the engine cradle, I will keep my eyes out for one.

As far as the trans goes, the problem is that there is a driveshaft running from the PTO on the passenger's side of the case out to the hydraulic pump unit under the bed, which is all plumbed into the cylinder and pivots. I could conceivably switch the PTO to the other side of the trans, but I'm not sure if I can make the hydraulics line up on the other side of the truck. The GM D60 sure would be a lot easier, though

[kwmech]

I am in the process of converting my 69 to 4x. Got the tires off and the new engine mounts installed. Ready to drop the front x-member and it dumped 8'' of snow....crap.

Have a dually chevy 60 waiting, making my own front spring hangar and also going to fit in a 56'' spring and try to get it to lay relatively flat so the truck isn't lifted to terribly high

[JJorgensen52]

Further research ... Chelsea indicates a different part number for the driver's side PTO but I can't determine why, they have the same drive gear ... so I think I can just flip the whole assembly over.

That said, I've got a line on an 84 K30 parts truck... which would make this infinitely easier.

Too many options!

[Longhorn 70]

Originally Posted by JJorgensen52

Further research ... Chelsea indicates a different part number for the driver's side PTO but I can't determine why, they have the same drive gear ... so I think I can just flip the whole assembly over.

That said, I've got a line on an 84 K30 parts truck... which would make this infinitely easier.

Too many options!

Other side of trans may make it different direction of rotation needed??

[StingRay]

I've thought about doing it too and the PTO is a concern also. I figured I'd just switch to an electric pump if I did it and not worry about building around the mechanical hydraulic pump. Things can be much simpler when the pto set up is out of the picture. It sure is nice on how fast the bed will lift with the mechanical set up though. Tap the gas and up she goes!

[Ol Blue K20]

No it's the shape of the case, if you swap sides it would be upside down to have output shaft facing right direction. The case would point up and it wouldn't have oil....

[JJorgensen52]

Originally Posted by Ol Blue K20

No it's the shape of the case, if you swap sides it would be upside down to have output shaft facing right direction. The case would point up and it wouldn't have oil....

http://www.adifp.com/ChelseaPDF/Chel...2100-M1_US.pdf

If you look at page 4, it shows the exploded view of the case. It's intended to be mounted with the shift fork pivot and switch facing up, but the actual gear housing is 100% symmetric top to bottom. It appears that I can simply swap the unit across the case, and install the selector cover in the correct orientation. I'll have to reverse the cable bracket to keep the correct pull direction, but I see no reason why it shouldn't work like that.

I'm going to call Chelsea and inquire about this in the next couple of days. They list I think 5 different models of PTO for this trans, and all of them show left or right mounting with reversed assembly orientation, except this single speed model. It shows a different part number for the driver's mount, which is not a 100 series and I haven't been able to find any information about it.

[Ol Blue K20]

Originally Posted by JJorgensen52

http://www.adifp.com/ChelseaPDF/Chel...2100-M1_US.pdf

If you look at page 4, it shows the exploded view of the case. It's intended to be mounted with the shift fork pivot and switch facing up, but the actual gear housing is 100% symmetric top to bottom. It appears that I can simply swap the unit across the case, and install the selector cover in the correct orientation. I'll have to reverse the cable bracket to keep the correct pull direction, but I see no reason why it shouldn't work like that.

I'm going to call Chelsea and inquire about this in the next couple of days. They list I think 5 different models of PTO for this trans, and all of them show left or right mounting with reversed assembly orientation, except this single speed model. It shows a different part number for the driver's mount, which is not a 100 series and I haven't been able to find any information about it.

Hmmm...that one is a different shape then the one in my tow truck...your right about the appearance but I would call they must have a reason. Let us know what you find out...

[JJorgensen52]

Moving ahead with this conversion. Just picked up a parts donor yesterday


Sorry for the crummy cell pic. Anyway, 1987 Sierra V3500 4x4 manual with a TBI 350. Stay tuned for a swap thread sometime soon.

[BLAZERMAN]

That's the way to do it!! You should have about everything you need.

[JJorgensen52]

Originally Posted by Ol Blue K20

Hmmm...that one is a different shape then the one in my tow truck...your right about the appearance but I would call they must have a reason. Let us know what you find out...

On this front, I just got off the phone with Chelsea and they said it's a clearance issue, the reverse idler support rib is too close to the output shaft to mount anything to the output shaft. Apparently they made a PTO with a longer shaft specifically for this application but have discontinued it.

I'm going to take some measurements, but since my PTO is the smaller (7/8") output shaft I think it might possibly be doable - maybe a little grinding needed?

[oldno7]

i'm watching these for my future build

[kwmech]

When I get mine done I will start my own thread for all to see

[Poppa Wheelie]

When you have a complete, similar donor, isnt is easier to just do a cab and wheel swap?

Or am I taking all the fun out of it?

[JJorgensen52]

Originally Posted by Poppa Wheelie

When you have a complete, similar donor, isnt is easier to just do a cab and wheel swap?

Or am I taking all the fun out of it?

I actually think this would be easier if the donor were in good shape, but this one has some pretty crusty sections in the frame, where my '72 has a VERY clean frame (odd for a truck from New England). The dimensions are close enough, that's for sure.

I actually looked at a couple before I picked this one up, because I needed something where, at the very least, the spring hangars and shackles were in good shape (beyond the axles), and finding that up here in the land of road salt is a tall order!

[D.PASSMORE]

I know this old, but have you made any progress?