How to turn a half ton into a 3/4 ton?

[Honest Bob]

Lug pattern is 8 bolt of the 3/4t instead of 6 bolt, brakes are bigger front and rear as well as I think most 3/4 ton had a full float rear axle instead of the semi float in the 1/2 ton. Really just swap over the axles with the wheels and the master cylinder and brake booster.

 

[peats]

I have a K20 truck with a very rotted floor and floor framing and there's a half ton for sale with a good body, what would i have to swap out to make the half ton a 3/4? I'm thinking the rear springs and differentials, anything else? Thanks

I don't know what your welding or fabricating skills are but replacing floor pans, rockers, inner rockers, A pillar bottoms, corners and cab supports is not really difficult, just a little time consuming. I would replace the metal instead of the cab. Your floor rust might be coming from a leaky cowl as well. Replacement parts are not expensive, think AMD or LMC as well as other sources.

 

[Tom31w]

I'm not going to swap differentials but I'm willing to swap the cabs. If I do end up replacing the bad body panels I'll take my cab off first and lay it on one side at a time on tires and weld standing up. As I recall both sides need inner and outer rockers and some floor and those short supports underneath. But the rest of the body is good. The floors rot from the snow from the boots, but it's pretty dry here. So thats how I'm probably going because I just got reminded that it might not even be legal here to swap cabs since the VIN is on the cab. I may go down to the courthouse and find out. The other thing I've been wondering about lately, regarding other upgrades is the fact that my insurance company asks (every time I add a vehicle) if I have done any modifications to the truck, I forget how they say it but it seems to let them off the hook if I do any conversions at all. I may ask an insurance agent about that. They sure do look for sneaky ways out of a obligation if they can work it
On the other hand, if all I had to do was swap those diffs, that might be the easiest way to go. Ill measure the springs on the 1/2 ton

It isn't illegal to swap VIN plates if it is done during the course of a restoration. I researched this a few years back when I was replacing rusted out the cab on my '77 K25. I would recommend ordering the correct rivets to use when swapping VIN plates, though. I dont think I saw what year you are working on so the VIN may be a plate on the driver's door jamb or may be by the windshield (depends on the year).if you want to check with your state, feel free to, just be sure to tell them you are restoring it.

 

[Craig Nedrow]

My cab was the same, found a doner, much easier. Yeah I did but all the parts, floor, inner and outer rockers etc, but much faster to swap the cab IMO.

 

[Ricko1966]

Better check with your DMV I'd bet you swapping VIN plates from 1 cab to another is illegal. I would bet that your Highway patrol can reassign the vin plate. And I would bet that the meaning of removing and replacing the VIN plate during a restoration means remove the VIN to do body work and paint and reattach it to the original cab.

 

[Strick]

It isn't illegal to swap VIN plates if it is done during the course of a restoration. I researched this a few years back when I was replacing rusted out the cab on my '77 K25. I would recommend ordering the correct rivets to use when swapping VIN plates, though. I dont think I saw what year you are working on so the VIN may be a plate on the driver's door jamb or may be by the windshield (depends on the year).if you want to check with your state, feel free to, just be sure to tell them you are restoring it.

I've been a few rounds with NCDMV & can tell you from experience that if you mess with the VIN, regardless of the situation; you're subjected to "reconstruction" and will need to undergo full inspection with DMV- not a local safety/emissions inspector.

 

[Jrgunn5150]

I'm going to make my 1/2 ton into a 3/4 ton, by taking the body on the right, and dropping it onto the frame on the left.

Any VIN/title advise, should come from your state authorities. They're all different, and you find many folks when pushed will say something like, oh, that was back in 89 lol. Call your authorities.

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[boltbrain]

Thanks, I'm still open to swapping in another cab. This one is pretty much just needing left inner rocker, the short channel frame under the A post, and the floor pan. On the right it's just the floor pan and short channel. But the big issue that worries me is the driver's (left) rocker is about 5/8" lower than the middle part of the floor where the cab bolts to the main rail with the main channel between floor and main rail. If I put a straight edge across the floor there's that hump in the middle of the floor. And I can't figure out how I would fix that except to jack up the entire rocker with it's posts, with no way of keeping it there. Seems as though the short channel under the A post has allowed the weight of the cab to sink there. It seems like it must be a common problem. If anybody has run into that and fixed it I'd be interested in knowing how it turned out. Thanks

 

[boltbrain]

Thanks, I'll look at the Tabco panels. I think I know where there's a cab without the hump in the floor and with less rust overall

 

[JBswth]

I have a K20 truck with a very rotted floor and floor framing and there's a half ton for sale with a good body, what would i have to swap out to make the half ton a 3/4? I'm thinking the rear springs and differentials, anything else? Thanks

If your frame is good, it would be easier to just swap cabs, and if necessary, beds, but if you really want to, you will have to swap the spring shackles, front and rear springs and shocks, axles, including brake drums and backing plates. I have heard both that the 1/2 ton and 3/4 ton frames are the same, and from others, that the 3/4 ton frame is a thicker gauge, so, yes, it is possible, but if you really use your truck as a truck, you would be wise to really find out the truth about that. If you mostly use it as a car, then you won't have any problems.

J. B.