Duramax swap?

[Drewbee]

Has anyone swapped a duramax into these trucks? I’m not seeing any on the search except for the smaller trucks.

[Pvmt-Pndr]

A duramax isn't usually a common swap, Cummins is the go to for almost anyone wanting to go diesel for the simplicity of it.

Physically I don't see a problem stuffing a duramax in my truck. Money is the thing that would rule it out for most people. For the price of a diesel (newer diesel anyway) for most people doesn't make economical sense. Sure they make a lot more power, sure they pull better but at the same time instead of paying all that money up front most can pocket it and go with a gasser. Not too many people that I see are daily driving a 50 year old or so truck. Given how often they're driven let's say you have to put $200 extra in gas vs a diesel a year.

Just throwing out random numbers here. A Dmax swap at bare minimum is going to cost $5k plus all the other things you'll need so I'd add $3k for random. An 8.1 can be had for $2k and no need to swap much of anything for another $1k ish. So roughly $8k vs $3k. It makes a lot of sense to save the roughly $5k and just put a little more in the fuel tank and live with a bb being a little more thirsty.

Don't think I wouldn't do it in a heartbeat if I was in your shoes though!

[Drewbee]

Yeah looks like if I want to go this route, I may not exactly be the first but I’d still be sort of a trailblazer. I have the cummins already, a nv4500 and np205. Call me a purist, but I think it’s be much better with a Chevy engine in there. However it’ll depend somewhat on the cost. I’ve thought about rebuilding the cummins and refreshing the nv4500. I got both of those for less than 2k which I think could be sold for more.

These 12vcummins engines are so mechanical and easy to put together if you can pay attention to what you’re doing. The duramax is a different animal...I’m always cautious when I walk into the unknown.

[AJC]

If you are going to do it a lb7 is probably the easiest/cheapest. Factory the lb7 made 300hp and 500tq. They don't have an egr or much of anything in terms of emissions. (except for California models) Around here you can pick up one needing injectors for like $2000. The Allison is good for over 300,000 miles but avoid a truck with a tune as its a quick way to kill one. I'm not saying don't tune it, but generally a tuned truck was beat on harder. Doing the injectors is not that bad and can be done for just under $1500. So for $3500 you can have a complete truck to take parts from. Then just sell off the rest.

Now what are you putting it in?

[Drewbee]

AJC,

I’m in the dreaming and planning stage right now. However, I’d love to build a 1972 crew cab K50 similar to the one rtech fabrications did, but instead of cummins, nv4500, and np205, I’d like to do a lbz duramax, Allison trans, and np205.

I have the axles, bed, and cab. If I buy a c50 I’d have the chassis and the second cab. I’d need some suburban doors to set the front and then I’d have four other doors to make the back two doors. The tricky part of all of this is the pillar between the front and back doors.

I’d also want to make a lot of it look stock with some minor modern updates such as interior, audio, and drivetrain.

Dreaming big I know but I don’t want to spend 70k on a new diesel when I could build me one and never need a new diesel. Also, it’d haul anything I ever throw at it. He most I’d haul is a fifth wheel with a tractor, or bobcat.

[AJC]

Drewbee, a lbz is nice but you are going to pay a premium for one. The money saved on a lb7 or lly could be put towards performance mods. With sporting mods the stock lb7 and lly is good till about 500hp flywheel then you need to start worrying. The stock allison is good to 400hp. Also stick to the factory transfer case and find a driver side drop front axle. It will be one less thing to worry about vs adapters and changing input shafts.

Most crew cabs builds seem to be a truck cab and a suburban. Some also make adding the 4th door look easy.

I think you will find the cost is going to add up quickly. Have you ever taken on a project like this? Do you have the tools to do it? I'm not trying to be discouraging, but is a big task that takes time and money.

Also if you don't need the latest and greatest creature comforts or the biggest engine numbers there is no need to spend 70k on a truck.

[Drewbee]

Thanks AJC,

I understand it’s a big undertaking and I know I don’t have to go spend 70k on a new truck. I have a 2005 cummins that works great and only slightly over 200k that I’ve replaced all the worn points so it should last for awhile. However, for me if I were going to spend my money, I’d rather spend it on this than a new truck.

As for the work, the mechanical side doesn’t bother me, the bodywork will be different but I think my metal fabrication side from things for the railroad would help. Also, have some good buddies that worked in auto body for years that want to help.

As for the tools, I have about everything and if I don’t, I got a welder, or I can go to work and make it on the lathe and/or mill.

I know it’s crazy, but I think respecting that it’s crazy let’s me go in with the right mindset knowing I may have to do certain things over and over until I get it the way I want and that I will probably never get what I have in it back out.

Thanks for shooting straight.

[Pvmt-Pndr]

If you maintain that mind set through out the whole build then you'll have no problems.

[txagincali]

Originally Posted by Drewbee

Has anyone swapped a duramax into these trucks? I’m not seeing any on the search except for the smaller trucks.

Yup!

Well not me personally, but I am swapping an LB7 into a C50 but with a Suburban chassis.

I was just like you about a year ago after the Duke started making its rounds and set out and bought my C50 and Cummins. Then after really looking at it with a measuring tape, that engine was a bit too long and the front clip was a bit too short for my liking and me second guess my decisions. They are able to fit, but the engine would need to be dropped down and the cab slightly elevated prior to fairly extensive firewall mods.

So I opted to go the DMax/Allison route. Scored a hellacious deal on a whole truck which needed 1 bank of injectors but am about even on it with after selling the bed. I bought a chassis off of a guy who just built a gnarly C50 with Duramax/Allison setup but its slammed on a G30 van chassis. Check out @Driftersgarage on IG.

I guess I need to start my build thread so that it doesn't look like you've got all these original ideas first! Haha

[Drewbee]

HA! Go for it TX! That would be a good way for me to learn as I go. Are you doing a suburban body as well for the b pillar?

Right now that's my biggest hurdle, as I don't want to mess up a good suburban body that someone could use for a cool suburban build - I'd love to have one myself, but that's a different topic.

Also don't worry about the ideas, I got plenty of them floating around

[GPSFAB]

Call me crazy, but has anyone thought of or has done a body swap with a later model c4500 or c5500 duramax truck? The frames are about the same width, you get modern steering, suspension, brakes and drivetrain. What’s everyone’s thoughts on that?

[Killer Bee]

I was kicking the idea around but decided to wait until I retire for more time and real estate to work with..

from the few days of phone calls I was not finding much in the way of direct swap help, especially for a K..

if you're going for it, may be worth an inquiry to see if this sold yet, good luck!

07 LBZ Duramax 6 speed Allison

[71blksuper4x4]

Are you just talking then about the C40-C50 platform? There have been a few duramax swaps (non-body swaps) done. Usually the biggest issue is the engine either sitting up to high for hood clearance, or too low that you have to notch the frame. Also, you want to factor in overall vehicle height to clear not only the front axle, but depending on drivetrain, your driveshaft to axle around the oil pan on these DMAX motors. I am still finishing up loose ends on my cab and then onto my LB7,Allison, and Ford np205 swap.

[Drewbee]

Hey Trevor

Nice build by the way, I've been keeping an eye on it.

Yeah I'm going to look at using the longer 1967-72 c50 frame and move the rear axle. Rtech fabrications did one that looks sweet and if you look at his pictures he put a dana 60 on the front, and 14 bolt on the rear and did a cummins, nv4500 swap in it.

I was going to go that route, as I have all the pieces except for the c50, but I want to be a little different. I have a bajillion other things going on with work, school, trying to invest, have somewhat of a social life, house, etc, and the projects end up being moved to the back.

I'd love to do an almost identical build like Rtech and use an lbz with allison, not sure on the transfer case but I do have a spare np205 sitting in the garage. Everyone is saying lb7 is easier, but I remember the lb7 having several issues and headaches. I'll probably end up rebuilding the cummins and nv4500 I have and selling those to offset the cost for a lbz duramax. I don't mind spending a little more because I want this to be my daily and I'd rather modernize this then go spend 60k on a newer diesel. Then I have something pretty unique that very few have.

[txagincali]

Drewbee,
I am still working on mine (which will be an LB7 & 5 Speed Ally) but I am not sure how any more difficult it would be to do an LBZ. They have basically the same bottom end and dimensions, it would all boil down to getting a standalone harness for it and the 6 speed (LBZ) is all $$$. I am doing LB7 because I have one, but I might swap to an LBZ once I get the whole truck put back together, or at least mocked up and driveable to test for power.

The one big problem I am running into however is with the DMAX/Ally and Drivers side drop Transfer Case. With the C50 frame having springs directly below (measurements on your other thread) it mounts narrower than the trucks of today and really the only front Dana 60 that would bolt in would be the 78-79 F250 which are worth their weight in gold to offroaders since they also bolt into Jeeps.

Newer Ford F250 Dana 60's have the spring perch cast into the pumpkin and make for one very short side and one very long side tube, not too mention being about 4" wider for mounting. The TC driveline angle might be too steep to reach with those dimensions, but I have not tried so don't take my word for it. I just don't think there is a good AND cheap bolt in 4WD front axle for the C50 with a Drivers Side Drop.

But that's not to say that it can't be done as I saw a 4x4 show on TV where a guy built a custom front axle out of a Corporate 14 Bolt. I thought this would be a cool way to go to keep it all GM but it would be just as much money into building that from scratch as it would for a 79 D60.

Just things to think about.

[68BlueBeast]

Originally Posted by txagincali

With the C50 frame having springs directly below (measurements on your other thread) it mounts narrower than the trucks of today and really the only front Dana 60 that would bolt in would be the 78-79 F250 which are worth their weight in gold to offroaders since they also bolt into Jeeps.

The 78/79 F250 Snowfighter/F350 D60 is in such high demand because it is a high pinion axle. It is also a direct bolt in for older Ford trucks with a low pinion D60. I don't know if it fits into your plans, but you could look at buying a pre-78 low pinion D60 and maybe save a few bucks. I think the biggest con would be the D44HD/D60 external locking hubs which no one has parts for anymore.

[Drewbee]

Hey Tx,

Glad you’re still working on yours. I’m slowly getting pieces here and there.

I’m still thinking the Chevy Dana 60 should work. I could have sworn if you look up the Duke build on here the guy said he used 1 ton single axles. I only know of a few passenger side drop 1 ton axles, Chevy/dodge Dana 60 and the Dana 61, which I highly doubt he used the latter. Also, I can see it’s passenger side drop in the pics too, so that’s why I narrowed it down. I believe I recall he used a cummins, Nv4500, np205 set up, which would be set up for passenger drop as well.

There’s also a YouTube video that shows more detail and he definitely didn’t change the front leaf spring set up. That’s what got me more excited because I can move the perches on the 14 bolt, not so much on the Dana 60. ��

Have you thought about changing the transfer case to a passenger side drop behind the ally?

[txagincali]

Hey Drewbee, sorry for the late replay but have been offline with the family.

You are right in that RTech Duke build runs GM PS drop axles with the Cummins/NV4500 and 205 TC. Jay Leno's Garage just released a new YouTube Episode where Randall goes on to describe the 66 Ponderosa version with similar setup. Fronts look just like leaf springs (lots of underbody footage in the video) with some trailing arms for the rear.

I have thought about running a divorced TC to the Ally for a PS drop but am re-evaluating given the space confinement I might have for the Trans crossmember and whether a TC will even fit. So now on to a new route of running a pre-97 Ford F-450 beam axle (2wd obviously) but with 8x6.5" lug pattern to match the AAM 11.5 rear.

Once I work out the computer complications with swapping an 04 motor into an 02 truck, I will start tearing down my donor and my tow rig (which is the 02 with an 01 LB7) and do the 2-way swap and clean up. Then maybe a build post to start once I have some substantial progress made.