1947 Panel Truck Frame swap with ’88 k2500

[Dan Bowles]

I know you already have the one but an X cab frame is slightly longer. About 141.5" or so. I started this with my son's truck once upon a time but he decided to stay straight axle. There is a seam under the 88's doors that takes the front cradle from boxed to the rear C channel. You can grind the welds out and cut the frame to length in 10 minutes. It is the same as doing an S10 swap using an X cab S10 frame. The 1 ton wheelbase is actually about 1.5" shorter than it should be so adding that back in you'd be about 140" for a rear centering wheel base.

There are several guys that have done this swap with pickups and they don't come out too bad. Late model HD rims look pretty sweet on these trucks, especially if powdercoated in a gray/silver color rather than the polished finish. 2008+ centercaps on them don't look so bad with them. I'll get you some photos from his truck as it sits.

If you are really concerned about width, you can swap a 1.5+ ton nose on and look at widening rear fenders. The one thing I would caution is make sure the damn rear wheels will come off with the fenders on. We have a set of rims with a deeper offset but couldn't get them onto the stock axle with spacers. We will swap to an 88+ 3.73 rear end here this summer but had to go back to the HDs because we just couldn't fit them onto the rear without dropping an axle because the fender hits!

Good luck. I'll keep an eye on this one. I've had 2 of those 3800s run through here and I dig them. 2 3800 pickups as well. I walked past Eli's 49 panel last night and thought "my suburban looks like a baby".

[Second Series]

Thanks for the feedback. I'm not too concerned with the wheels sticking out of the wheel wells, just addressing the issue beforehand. I'm kind of dragging my feet at this point, waiting until fall to start. I'm going through the different systems, planning how each will work. I'll use the stock gauges, so a bit of design work there. I figured out how to keep the stock ignition switch and foot starter. I'll look at everything else on the wiring diagram, I'd like to eliminate the bulkhead connector if I can. I'll look into building a drive for the speedometer too.

[Dan Bowles]

Originally Posted by Second Series

Thanks for the feedback. I'm not too concerned with the wheels sticking out of the wheel wells, just addressing the issue beforehand. I'm kind of dragging my feet at this point, waiting until fall to start. I'm going through the different systems, planning how each will work. I'll use the stock gauges, so a bit of design work there. I figured out how to keep the stock ignition switch and foot starter. I'll look at everything else on the wiring diagram, I'd like to eliminate the bulkhead connector if I can. I'll look into building a drive for the speedometer too.

I think it's Bob's Speedometer in Michigan that can do the electric to mechanical speedo conversion. I've talked to them a bit but not gone any further than that. It's around $250 IIRC but something I don't know if I could make on my own without some study!

[Second Series]

I just looked on Bob’s website, they show the Cable-X, Cable-X site lists it at $340. Dakota Digital is $285, Speedhut is $360. There may be others, this is just from a quick search this morning. I’ll look into reviews of what’s available.
I read a post about converting a ’89 Blazer transfer case mechanical to ’90-’91 electrical speedo, so it may be possible to go the other way. I also read that Dodge used a mechanical speedo on the NV4500 at some point. I have a 5LM60 now, and I understand that is identical to the NV3500 on the outside. If I can get it set up with a mechanical speedo drive, I’ll go that route. I’ll still need the electronic signal. If I have to remove the tone ring, I may be able to get an in-line VSS. Stealth Conversions made one for the 4-pulse system, there are bound to be others. This is partly speculation, I’ll take my time and create a detailed document.
Dan, how about a pic of your son’s truck?
My k2500 is the 6-lug. Does the 8-lug k2500 have a wider tread? I read where someone swapped the 6-lug to 8-lug spindle and modified the upper A-arm, that’s my plan. The diffs are 3.73, the ’88 8-lug rear in the ’47 is also 3.73. I was concerned about how the rear works with the RWAL (Rear Wheel Anti-Lock) system. I don’t see any wires to the rear axle. The schematic show the VSS supplies the signal for that system, so it should be good to swap the rear.

[Second Series]

I intend to keep the original key switch in the ’47, and modify the foot button to work with the ’88 system. My list of objectives:
1. Retain the original ignition key switch and foot starter.
2. Adapt donor circuit to function from original key and footbutton
3. Modify foot button bracket to actuate momentary switch, relocate switch-originally on starter.
Is there room between the lower firewall and the rear of the engine?
First I’ll identify how the donor key switch functions.

From the manual:
STEERING COLUMN HARNESS CONNECTIONS
The steering column harness branches from the instrument panel harness and then to the turn signal or multifunction lever switch connector, the windshield wiper connector, ignition switch connector, the brake pedal ' 5 switch, connector, the dimmer switch connector, the , back-up switch connector, the position sensor connector ’ and the horn switch. Refer to figure 24 and to ACCESSORIES (SEC. 9) for the multi-function lever switch.

This image shows the Ignition switch connector, 232.

[Second Series]

From the manual:

[Second Series]

There is also a switch in the lock cylinder that triggers the buzzer if the door opens with the key still in. I won’t have that.


Here is a diagram of the ’88 ignition switch.

[Dan Bowles]

Originally Posted by Second Series

My k2500 is the 6-lug. Does the 8-lug k2500 have a wider tread? I read where someone swapped the 6-lug to 8-lug spindle and modified the upper A-arm, that’s my plan. The diffs are 3.73, the ’88 8-lug rear in the ’47 is also 3.73. I was concerned about how the rear works with the RWAL (Rear Wheel Anti-Lock) system. I don’t see any wires to the rear axle. The schematic show the VSS supplies the signal for that system, so it should be good to swap the rear.

My local guy swapped his completely over to 8 lug with little or no effort. Swapped spindles and the axle. I don't think there is a significant width difference. Anti-lock I think just was a speed sensor in trans for 88. Nothing high tech there and you can by-pass it by ripping out the ABS box and running brakes direct. Those things are probably failed by now anyway!

I'll get pics of Eli's truck soon. He's tearing stuff apart again working on some body work right now. It's been up and down over the last 10 years. A giant wheelbarrow full of storage for at least 6. The nice thing was getting a set of 93-94 extended cab bucket seats. They sit almost perfect on the riser and give you a flip forward/slide forward option on the passenger seat for rear access if you need. No major mounting issues, either because the frames are about square and flat unlike about every other front seat you run into!

[Second Series]

I have been reading build threads here and found a few full size frame swaps very inspirational.
I signed a contract and put a deposit down at the shop, now I’m waiting for space to open up so I can drive the trucks there. Once the build starts, I’ll need parts. I don’t know what all I will need, but some of it is obvious.
I created a spreadsheet of available parts. I started at one on-line parts catalog, and looked through each category. I picked what I think I will need and put it on the spreadsheet. I looked at a few sites, and was able to compare prices. I placed an order today for some parts with one company that is having a holiday sale.
I realize some things won’t be needed for awhile, like window gaskets, but I got some anyway. This was a small order, I may be more cautious in the future. Some parts are common to the suppliers, other parts seem to be at one or the other. It’s random. I am also looking through discussion threads about what parts to avoid, or who sells the best parts. This helped me choose the right outer rubber window seals.
There is a sale this holiday weekend at the wrecking yard. I’ll look for seats, a steering column, spindles etc. I’m committed to this build now. At some point I’ll have boxes of parts. I don’t intend to have boxes of parts waiting for years. I plan on going full speed ahead!

[Second Series]

I received one box of parts minus a few on back order. The back ordered parts arrived this week, but one part was off by a couple digits so I’ll have to wait until they get the right part in stock before I can return this. I spent some time in the wrecking yard, scored a couple front seats out of a Astro van for $40. I tried to get the front spindles off a k2500, but got burned out after two hours. I didn’t have the right tools, my time was running out, but what I mostly needed was a cheeseburger. On the way out I saw a barebones steering column in a jeep. I’ll try to get back there after work soon. Yesterday I ordered some bullet tail lights.
Two weeks ago I drove my panel truck for the last time, as it is, to the resto shop. This week I drove the ’88 GMC there, the panel truck was being dismantled and they hit me with a healthy bill. Today I got a call that the GMC bed has been removed and most of the panel truck parts are ready to get blasted. I thought I could recoup a little by hauling the extra parts off myself, but I don’t have the time, don’t want to pay to store them, so it’s off to the scrappers with the ’88 GMC bed.
I’m still trying to decide on the color. I had wanted a very dark purple that looks black, when I started driving the panel truck over 20 years ago. I still think that would be cool, but something subdued might be better for a daily driver. I’m considering two-tone grey, or grey and midnight purple. The resto guy said he likes to use the vintage colors on builds like this, but that it’s my decision. I have been looking at the vintage colors, but in 1947 the Forester Green was the standard. There were a handful of options, and two-tone wasn’t available until ’54 then it was just white for the top half. I recently went on a road trip a saw a couple vehicles with a light blue on the lower half and cream on top, that I like. So now I’ll think about the two-tone grey, and the blue and cream, and I have some model paint to play around with a dark purple.
My parts spreadsheet is growing and I need to order all the hard parts before any paint. I’ll add windshield washer nozzles for example, and whatever bits and pieces I can think of. I also need to continue engineering the ’88 wiring to the ’47 controls. I just read that the brake light switch has multiple contacts, so that will all have to function one way or another. Moving right along!