LB7 into a 1983 K20

[jstolk2]

I apologize ahead of time for anything dumb I might say or do. I'm a complete noob. I'm also a newbie to the Diesel world. I've always had gassers. With that said:
Its time to resurrect my 1983 K20. It was my first truck. Bought it when I was 15(I'm now 30). I've already got all new body panels for it. I was just going to freshen up the 355 that's in it and call it good. But the other day a friend of mine made me an offer I couldn't refuse. He sold me his wrecked (cab damage) 2003 2500HD Duramax ECSB. Truck has just over 100k miles. And the Allison only has 5k miles on the rebuild. So now I'm quickly developing a new plan! I've seen amazing LB7 swaps online and on this site. I doubt my project will ever hold a candle to the ones I've seen on here. But I ultimately just want it to be reliable, and just a decent looking usable truck. Initial plan is use the LB7, Allison, Tcase, and rearend from the 03, and get a Ford axle to run up front. I'm obviously just starting the planning stages and I'm trying to gather all the information I can. My initial thoughts are to take my K20 down to the frame, blast it, and box in the whole frame so that I can actually utilize all the pulling power the LB7 has to offer. Would this be a good first step?
Any wisdom, thoughts, or foresight would be greatly appreciated.

 

[clrussell]

Welcome to the forum! There's a few guys doing swaps right now so there's a lot of info floating around. I believe one of the members is doing a lb7 swap into a 85 k5 blazer.

I like your idea to keep the dmax stuff together and run a ford axle up front. If I was going to do one that is what I would do if I was keeping the old frame.

That being said if I was doing this swap I would be thinking very hard about using the dmax frame. Mostly for the updated suspension brakes etc..

There's a guy on the 67-72 chevy truck forum merging a 71 and an 03, last I saw of the build it looked great! I'll try to find the link real quick.

Get your self the beverage of your choice, find the search tool, and prepare to read a ton and learn!

 

[clrussell]

Here's the thread

http://67-72chevytrucks.com/vboard/showthread.php?t=623193

Been a while since I looked at it so I'm not sure how much progress he has made.

 

[jstolk2]

Thanks for the link clrussell. I'll be sure to read that sometime today. Swapping the body onto the Duramax frame has definitely gone through my head a lot also. But my main concern there is the wheelbase difference. I haven't actually taken a tape to either of them, but from specs I've found online the Duramax I bought has a 143.5" wb, while my truck has a 131.5" wb. I haven't gotten the two truck side by side yet, but I'm also concerned that since the 2003 is an extended cab, and my 83 is a standard cab, that the contours of the 2003 frame would not fit my 83 body very well. But I'm still definitely researching that route as well. I do not have enough overhead room in my garage for pulling cabs, and since its winter here in the midwest right now, I will not be starting this project until it warms up in the spring. So for the next two months or so, I'll be doing a lot of reading, measuring, and planning. But I cant wait to get started!

 

[catman3126]

I did a ls swap from a 04 2500hd in my 86 k10 and I did alot of measuring of both frames because initially i wanted to put the 86 body on the 2500hd frame and shorted it to make it fit the short bed. I know a body lift would have to be used and custom fabbed cab and front body mounts would ahve to be made due to the HD frame being aroudn 10 inches wider at the firewall and engine compartment area. it can be done but theres alot to it. I ened up putting the LS 6.0 engine and trans in the K10 and using the disc brake rear end from the 04' and a 1990 suburban transfer case that had the VSS built in to keep the pass side differential in the front. you won't be able to do that though due to the allison having a different spling count on the output side then the 4L80E I used so your better off to do the D 60 front end swap from a ford. I have a 03 ZF6 LB7 i have been looking everywhere to find a 89-91 square body crew cab to do a swap into but so far havent found a clean not beat up one to buy. still looking though.

 

[mackthehack]

Either route you go. Keeping your k20 frame or using the dmax frame you can make things work. With research, fab skills and the tools needed. I'm starting a similar build but with a c10. I'd go with your k20 frame beef it up a little and run a 78-79 Ford hp Dana 60. You can buy frame reinforcement kits from DIY4X. If that Duramax powered truck was 2wd you can pick up an NP205 tcase out of a Ford and run that in a divorced setup.

 

[jstolk2]

Thanks for the info Catman. Yeah, as much as I'd like to keep the frame from the 03, I'm just not sure if I'm confident enough yet with my fabrication skills to figure all of that out. You're a lucky man to have a ZF6. Those suckers are hard to find! It's a dream of mine also to find a crew cab OBS and do a conversion. There was a very clean 85 with a short bed on it running around here for years. Never got a chance to talk to the guy, but I never see it around anymore. I wish I would have gotten my hands on that one.

 

[jstolk2]

Thanks Mack. The Duramax is a 4wd. Is a frame reinforcement kit better than boxing the frame, or is it something that would be done along with boxing the frame? I haven't got much for fab tools yet. I've got a 110/220 mig welder, a 220 stick welder, and a plasma cutter. All the fab I've done up till this point has mainly been farm use. Doesn't have to be pretty, just has to hold. So a lot of this will be new to me.

 

[catman3126]

Also with your K20 frame you will have alot of work over to do on the cross member under the oil pan and will need a small body lift as the allison won't fit under the hump, oh and don't foget the radiator core support the duramax radiator and intercooler is much wider. Lonnie on here is doing a swap into a K20 and has some pictures of his work. http://www.duramaxdiesels.com/forum/showthread.php?t=2447

read through that theres some good pictures and info there.

 

[jstolk2]

Yeah, I've seen Lance's swap project. Looks phenomenal. Unfortunately, looks like he hasn't updated his thread in quite a while. I cant wait to see his finished project. His other vehicles look top notch as well. If I remember right, I think he said he needed about 1.75" body lift to make it fit. Do you know how he reinforced his frame? I don't remember reading that he boxed it in.

 

[mackthehack]

Thanks Mack. The Duramax is a 4wd. Is a frame reinforcement kit better than boxing the frame, or is it something that would be done along with boxing the frame? I haven't got much for fab tools yet. I've got a 110/220 mig welder, a 220 stick welder, and a plasma cutter. All the fab I've done up till this point has mainly been farm use. Doesn't have to be pretty, just has to hold. So a lot of this will be new to me.

The reinforcement kit is a kit that boxes the frame. You can definitely get a lot done with that wire feed welder and plasma cutter. I did my sas on my truck with a 110 welder and inner shield wire and wheeled the shit out of it with no problems or worries.