K20 Vs K30 frames

[66gmcguy]

Howdy all. I am looking for some opinions. I have a 1982 GMC K2500 camper special and the body on it is completely smoked. There isn't one decent body panel on it, so the plan is to slowly collect good body panels, paint them to match, then put together a nice clean truck. I recently picked up a K30 parts truck for the cab that's on it, and I was thinking about using the chassis too. But I just discovered that the section of frame between the front bumper and engine crossmember was cut off and replaced, and whoever replaced it did a piss-poor job aligning everything, so now I don't want to use this frame. I do have a clean C30 chassis that I could use and put all the 4wd stuff from the K30 on, but it seems like it's going to be a fair bit of work. My question is: is it worth it to go through all that trouble just to get a K30 chassis? My goals with the truck are to eventually put a duramax or cummins in it and use it to pull a 10k pound trailer. As far as I can tell, the only difference in the frames is that the K30 frame is taller underneath the cab. The steel is the same thickness between the K2500 and K30. So what do you guys think? Keep the K2500 chassis or do the work to make a K30 chassis?

[kwmech]

Is the section of the K30 frame that is funky not useable at all? Doing a diesel swap is going to entail work in that area with reinforcement anyways. How bad is it?

[66gmcguy]

Originally Posted by kwmech

Is the section of the K30 frame that is funky not useable at all? Doing a diesel swap is going to entail work in that area with reinforcement anyways. How bad is it?

It's not that it's not useable, it just looks terrible and isn't lined up at all. And I also don't know who welded it and what their skill level is, so I'd rather not use it.

[Dead Parrot]

If you don't trust that K30 frame with the poor welding, don't use it. You are about to do a lot of work to make a truck and you don't want to be always worrying about the frame. Let someone else have the fun of fixing that frame and getting it properly aligned.

Are you hard set on a 4WD? You could put a dually axle on the C30 frame and have a nice towing setup. If you really want a K30, see if you can find a CUCV being parted out.

[LT7A]

A 3/4 ton 4x4, a 4x4 1 ton parts truck, and a two-wheel drive 1 ton frame - have I got that right? As I was reading your post, I was thinking, heck yeah, build that K20. But if ever a civilian needed a one ton, it's when he's towing 10,000 pounds with a 900 lb engine. Here's what I recommend, so that you can keep a running, driving truck: use the good body panels off of the K30 to fix up the K20. See how it handles towing 10,000 pounds. Fix the k30 frame with a chunk off of the C20, unless it's easier to swap the K30 components onto the C30 frame. Build the diesel drivetrain onto the C/K30 frame. And then swap over the good body that you've been driving this whole time as a K20. To summarize, in my opinion, it's very important that you have that taller section of frame under the cab. That's what's going to help handle all the power of your diesel doing the work to tow all the weight you'll have behind it. And if you didn't want a cool project truck, you would have a late model Duramax and be watching Netflix right now.

[66gmcguy]

Originally Posted by LT7A

A 3/4 ton 4x4, a 4x4 1 ton parts truck, and a two-wheel drive 1 ton frame - have I got that right?

You are correct.

Originally Posted by LT7A

Here's what I recommend, so that you can keep a running, driving truck: use the good body panels off of the K30 to fix up the K20. See how it handles towing 10,000 pounds

This is likely what I'll end up doing.

Originally Posted by LT7A

To summarize, in my opinion, it's very important that you have that taller section of frame under the cab. That's what's going to help handle all the power of your diesel doing the work to tow all the weight you'll have behind it.

Good point. Unless I find another clean K30 chassis, I'll likely just swap all the 4wd stuff onto the cleaner C30 frame.

[wazzabie]

Not sure I follow. I would be looking for a new frame if something was in question.

[66gmcguy]

Originally Posted by wazzabie

Not sure I follow. I would be looking for a new frame if something was in question.

Have a 1982 GMC K2500 (Same as K20.) Body is smoked. Want to replace body by piecing stuff together over time.

Bought a K30 roller because it has a super clean cab. Thought about using the chassis on this truck too but just discovered it's damaged and don't want to use it.

Have a clean C30 chassis. Thinking of taking all the 4wd stuff off the damaged K30 frame and attaching it to the C30 frame, effectively making a clean K30 frame, but wondering if it's worth the effort since there doesn't appear to be a major difference between the K20 and K30 frame, apart from the frame being taller under the cab on the K30.

[66gmcguy]

I realize the easiest thing to do is to buy a complete K30, but K30s are nearly impossible to find in this area, and if you do find one that isn't completely hammered, people want stupid money for them. Especially here in the bay area, where people seem to think they can charge a 200% markup for any classic car/truck.

[wazzabie]

I think the k30 frame is thicker compared to the k20 frame. Someone had taken measurements.

[66gmcguy]

Originally Posted by wazzabie

I think the k30 frame is thicker compared to the k20 frame. Someone had taken measurements.

Yeah that's what I read too, but I just went out and measured all three frames. The C30 and K30 measured .21" and my K2500 measured .23"

I also just checked the SPID sheet. My K2500 has the Heavy Duty Chassis option (RPO code C6P.) Would that make it sort of the equivalent to a 2500HD, like on the newer trucks?

[THI]

The Camper Special option took the normal 3/4-ton heavy duty frame (same dimensions as the half-ton frame but with thicker metal) and added the 1-ton springs (rear springs rated 3,500# each) and shocks. I have a 1978 C20 with the Deluxe Camper Special option and replaced all of the springs last year - even the front were of the 1-ton verity. It you have a good 1-ton frame, it is taller than the HD 3/4-ton frame so you would need to use the trans/t-case crossmember from the K30 if you decide to convert the C30 frame to 4WD. if I were in your shoes and had a good C30 frame and the parts to convert it to a K30 I would go that route. I had a 1986 K30 parts truck I bought for the Dana 60 and 14-bolt rear to put on a 1975 K20 Suburban I no longer have. If the frame on the K30 had not been rusted so bad I would have kept it!