47-59 54, 6400 cab switch

[Bowtie348]

Was thinking about trying to put the cab of my 1954, 6400 on my 1985 chevy 1 ton chassis. Ii have not done much research yet, just thought I would check on here, there's some with alot more experience on these trucks. Will it be a straight up headache to try this ?

[mr48chev]

It should be fairly simple as far as frame swaps go. The main issue you will have is setting the inner fenders down over the rise in the frame over the front suspension and the upper A arms. That will take some trimming. For that I'd setting the cab with nose on the 85 frame and center the wheel opening on what would be the wheel center and trim the inner fenders where they need to be trimmed as you go. That and building mounts for the cab on the frame and figuring out a cross bar mount for the radiator support and you should be in pretty good shape.

I'd run the pedal and hydrovac off the 85 and mount it on the firewall and put a reinforcement plate on the inside of the firewall. That brake setup is too good to try to do anything else with even though I think firewall mounted brakes are ugly but works great and practical and matches the chassis wins this time.

I can't find the photo of the 77 1 ton chassis sitting on the bed of my 77 1 ton flatbed to show how the frame rises over the front suspension but you may already have that figured out. Width wise the frames are within a half inch in width the whole length.

[leegreen]

check the front wheel width, the 85 wheels will probably stick out past fender lip a couple inches. Ok if you want a big truck look, but not if you want a low look.

Mr48chev is the expert, but I think the overall length of the 6400 fenders is the same as the 1/2ton. So check the dimension of 85 from center of front tires to front of steering box, you are going to end up cutting the frame back to near the steering box and depending on height you set the cab and front sheetmetal above frame the steering box is into the grill.

Also using center of tires as reference point check where the front and back of engine will fall within the '54 engine bay, see if you have to remount the engine and trans and make a new driveshaft and if there is room for a radiator.

[Second Series]

'85 I believe had the gas tank outside the frame rail, 2nd gas tank was on the other side. You won't have room for the stock tank. Later years had the gas tank inside the frame rail/ wider frame, 2nd tank was under bed in the rear. I used an '88 GMC for my 3800 swap. line up the front fenders with the front wheels to determine cab location, everything fits and the stock height was maintained.

[mr48chev]

I'm not an expert in my estimation but I am good at finding info and have saved a ton of info over the years.

This print is from the 54 Chevy truck pfd from the GM Heritage center vehicle information kits that has a lot of correct factory information for 54 Chevy trucks.

Outside of front fender to outside of front fender on the 6400 is 74.56 inches.

3000 series trucks are 72.94 across the front fenders. That is 1.62 wider than the little trucks

Width of an 85 truck body at the widest point (not dual fenders) is 79.6 and the tires sit well within the fenders on the front if you use dual wheels.

One thing to watch, The center of the wheel to firewall on all AD conventional cabs is 17.75 inches. I haven't gone out and looked at the front section of the 77 frame and front suspension I have saved for my 4100 (just plan a crossmember swap) but you may have to set the cab a bit higher off the frame than you would with a flat frame rail. The slant of the toe boards may take care of that and make it a non issue though.

I'd have swapped the 4100 cab and nose I have over to the 77 Dualie frame I hauled home if my daughter didn't want to have a flatbed with a hoist on the 51 4100.

One last thing. If the 54 6400 has a title make sure of which serial number is used as the vin. A lot of states used the engine block serial number as the vin rather than the cab serial number and if that is the case and you have the engine block with that serial number still in the truck do not get rid of that block until you have had the truck inspected and have the vin on the title updated.

Also if you have the title to the 85 keep that title or documentation that you own that frame legally until you have the truck inspected.

I'm going to say get yourself a three ring binder and some plastic page savers and put together a build book for the truck.

I'd add photos from the day I bought it in that section.

In that book put the paperwork or photo copies of for the 54. That includes title, bill of sale or receipt for when you bought it.
Put the documentation on the 85 that shows that you legally own that chassis.
I'd probably add photos of the donor truck. including the roller chassis especially if that roller chassis also had the engine and trans that came with it that you intend to use.

If you are using the engine, trans and rear out of the 85 life is good as you have documentation If not you want bills of sale or receipts for engine and trans and the rear if you changed it.

Inspectors don't care where you bought the goodies and trinkets that you put on the truck but you have to show that you legally own the frame, engine, transmission, rear axle and the cab. The more tidy you have your ducks in a row the simpler it is to get things done.