The Stovebolt Site Forums The Shop Area General Truck Talk AD Cab Questions

I know I am asking for a lot of info, so bear with me. I have some experience with the 41-46, but little with the AD trucks. I did a search on AD Cabs, and could not find detailed differences between the 47-55 1st except for the mounts. Is there a expert out there?

Has anyone replaced an AD Cab from a 3 window to a 5 window? Are the AD Cabs, doors, windows etc. interchangeable? And with the big bolts? When did they come with vent windows? What about mounting of fuel tanks? Instruments?
I think you can see where I am going.

Any and all assistance appreciated.

Dale

Jim Carter's catalog has an excellent section at the front describing year over year changes:

http://www.oldchevytrucks.biz/47_55/t1.asp?page=6

The above page will tell you exactly when the doors changed for the push button handles as well as vent windows, etc.

AD body mounts changed? First I've heard of that. If I misread or that info is wrong, you should be able to swap out cabs between years on AD trucks. There is no mention of mounts changing in the JC page cited. The new aftermarket cabs are interchangeable so why not?

Doors through '50 had no vents and pull-down handles. 1951 doors had vents and pull-down handles. '52 and up doors had vents and push-button handles.

Everything else you mention should fit.

I think the cab mounts were different on the '47-48's than the later years.

Cab mounts changed in 1949. I think that the change was from four pads to 2 pads plus two side shackles for the rear cab mounts. I do not know if the frame changed much in 1949 (cab shackle attachment points?) but there were only a few minor changes inside the cab.

Here is an interesting 1984 article about changes in Advance-Design trucks.

Yes, the rear cab mounts changed sometime about 48-49.
The earlier ones have a single rear mount in the center back of The cab.
Late cabs have a mount on each side at the back of the cab.
I have both a 48 and a 52, and they are indeed different.

The cabs can still be switched, but the right mounts need to be swapped on the frame. Probably simpler to put an early cab on a late frame, may only involve drilling two 3/8" holes. The other way around will take 4 holes and some brackets.

Fuel tanks moved from on the frame to inside the cab at about the same time, 48-49.

Big bolt cabs follow all the same rules as the small truck cabs, and in fact they are identical and swappable.

That's how I understand it as of now, please correct me if I am wrong,
Grigg

Also the gas tank started out underneath between the frame at the rear and then it was moved inside the cab for safety !! From the factory photos that I have seen, it seems that the 47s had a double cab lower wall in the rear when the tank was underneath.

My 48 has the inner sheet metal where the tank would have been. The tank was mounted outside the frame.
In smaller trucks, same year, the tank was inside the frame.
I think 1949 is the year the tanks came back in the cab. On the other side of the coin is late 47 and most if not all of 48 the tanks should be outside of the cab.

Grigg

I also believe that the cowl vent moved from the side to the top of the cowl. Maybe from 50 to 51. My 51 is on top.

My 48 and my 52 have a flip open vent on the top of the cowl.

Todd M, your confusion may be that the cowl side vents did change somewhat in the AD trucks, but I forget the details, seems some had both side vents, and some not???

Grigg

The curved glass windshield and slightly different dash on '54 and '55 1st are a couple things I didn't see mentioned already. Also know that the dash is significantly different on a '54/'55 1st GMC from the Chevy.

Oops, brainfart here.... for some reason I thought AD started in '49. My bad.

Grigg,
The AD cabs traded the side cowl vent for the vent windows in the doors in '51. All AD cabs have the top cowl vent.

I have both an early '49 (January) and a late '49 (August) and the cab mounts are the same -- two bolts with pads & spacers in front, two shackles (one on either side) in back.

The only difference between my two cabs is how the center of the headliner attaches (early one has the screwed on bow, the later one "floats" (has a ribbed retainer that the edges press into).

Woody -- no brain farts -- only opportunities to learn The Advance Design series started in the second half of '47.

Regards,
John.

The left-side cowl (driver's side) ventilator was removed in 1951. The top cowl ventilator and the right-side (passenger's side) ventilator was there all Advance-Design years.

In late 1949, two cab-interior changes were the cab door-opening windlace track and the headliner bow was no longer screwed in.

A subtle change that I think people bring up during this type of discussion is a slight change in the appearance of the firewall), but I do not recall which year.

The 47's had a smoother looking firewall, and I think in 48 they changed and were the same, or close to the same, for the rest of the AD years.
It would be good if someone had pictures, as I've never seen a 47 side by side with the later model to compare.

Grigg

The upper cowl vent was on all of them, the drivers side vent was eliminated when the vent windows were introduced.
Tim, just spent the last hour over at your house, are the LCVA articles new, I hadn't seen them before. And thanks a bunch for posting the Factoids Page, that looks new also, http://69.65.24.123/~y3mk6hrx/A-D_factoids/
I found a few broken links in there but great information. For any of you guys that haven't seen this stuff, grab a cup of coffee and go visit Tim this morning.
Thanks Mr. Lederman
Denny Graham

I have a factory manual supplement for 1948 to 1950 printed in Oshawa. I believe it mentions new cab mounts which I presume were the rear mounts. It also gives details of how to repair cracks at the front of the cab and on the radiator. The portion on the radiator shows the installation of the cross bracing rods for the rad support. I think maybe that the early AD trucks had some problems with twisting because of the rear mount design.

Guys - All AD cabs have top cowl mounted vents. The 54-55 1st are shaped different becuase of the new one piece windshield. The Side cowl vents were eliminated in '51 with the advent of the new door mounted vent windows. I agree with everybody on the body mounts. One thing that a lot of guys don't know is that the firewalls are slightly different thru some of the AD years. The firewall on the '47-'48 are the same. '49 is different with a rain trought added on the top of the firewall, '50-'55 1st have the rain trought plus added embossed strips on the firewall for added rigidity to the firewall.

Hey Fred, I got a great idea, why don't you send a copy of that supplement over to Keith at TOCMP so he can archive it for posterity. The more of this reference material that we have available for the historians the less, "My memory of it was....." We get an awful lot of misinformation from those fading memories that distort the facts and then it seems to take on a life of it's own out here on the WWW.

Denny Graham
Sandwich, IL

Didn’t even think about the one piece windshield. This is what I was thinking.
I am looking at a 3 Window 1954 AD truck, ½ ton. Stock with the 235 full pressure engine.

(Only downside on the original 54 that I can think of was the closed torque tube v the open Hotchkiss on the 55 1st.)

If I acquired this 54, could I purchase a 5 Window big-bolt, (they seem to go for a lot less,) and swap out the cabs? Will the 47-53 two piece windshield adapt to the one piece windshield? Were the cabs modified in 54 at the windshield opening? Or is this a slam dunk?

Will the cab dashboard mounts of a 47-53 adapt to a 54-55 1st dashboard? Is the value $$$ of an AD worth more as a 5 Window, or 3 Window? Of the two styles, what creates a larger interest of the prospective buyers?

For me personally, years ago, I had a 55 1st Model D/Series 3100 5 Window Deluxe, and I just can’t seem to shake it out of my desires to have it in my stable. Am I nuts, or ???

The 5 window cab is most likely more valuable; most people think it nicer and safer, and thus more desirable.

The same cab (in each year) is used on different-sized trucks.

Messing with pre-54 dashes and windshields in 54/55 cabs (or visa verse) would be a challenge for most people.

I think by most accounts people put a greater value on the 5 window cab. I know it makes a difference to me and most of the restored trucks of this era that I see are the 5 window. I also know that I have seen some article out there about cutting the cab at the belt line and the roof to fab in the back half of a 5 window cab to a 3 window cab. I also know that the vendors now sell a 5 window patch panel that would do just this. If you were paying someone to do this I do not know if the increase in value would offset the cost.
my .02
steve

46Canopy - The dashes are welded in on the AD trucks. The shape of the dash at the windshield on the 54-55 has a different arch to it than on the 47-53. If you are a sheet metal fabricator you could probably customize it to fit. That sounds like a nice challenge that I would take on. It would really mess people up looking at it. I'm all for that. As to the $$ value of 5 window cab vs. 3 window cab - it all depends on who you talk to. Old Cars Price Guide does not specify a different value between the two cabs.-wbrowne

So it looks as though if I want a 54/55 1st 5 window donor cab. The easy way for me would be a cab swap of the same years. I am no welder or fabricator. By the parting out of the big bolt, the resale of the unused parts would probably justify the cost of the R & R.
Thanks again to all bolters for your incredible insight.

Dale

46Canopy, I changed cabs from a 3 window to a 5 window on a '54, it's a lot of work, but was pretty much of a bolt on swap. Biggest problem is lifting the cabs, but I used my engine hoist and some 4" X 4" posts and ropes.