Heat Shield holes in 4x4 cab???

[DANTIP]

Shown below is a stripped cab from a frame-up restoration of a '72 4x4. The SPID didn't have A/C listed and I was questioning the originality of the cab. The owner sent me a few pictures and it certainly looks like an original A/C cab. Upon closer inspection, I noticed holes in the cab floor on the passenger side that would have been used for a heat shield on a Big Block truck. The VIN tag is riveted to the cab with the rosette rivets and looks "original".

Assumptions:
1) The heat shield was a big-block only item.
2) High-hump trucks without the heat shield did not have the holes in the floor for the heat shield.
3) There is no other reasonable explanation for the heat shield holes other than the cab was originally on a Big Block 2WD truck.

This may not be important to too many people, but this is an expensive truck and I am willing to pay more for an original truck than one that has been put together from multiple donors.

Lastly, is there any other differences I can look for in these photos?

Thanks for your feedback!!

[D.PASSMORE]

Thoughts:

1. Maybe a PO/dealer add-on?

2. Cab availability during production at plant?

Also, I have a 72 Chev BB deluxe (rear outer light) cab in my barn, A/C, auto, high hump. I'll check it - where are the holes located?. UPDATE - if intrested: I checked the 72 Chev BB cab - holes and checked my original 72 - 4x4 cab - no holes.

BTW, I have a few sets of GM rose-bud rivits. Going to use a set for my cab conversion - from ^^ to a 72 3/4T 4x4. You can still find them. So...

Of course 72 cabs had the cab vent on driver side lower rear door pillar and no top WS Frame hump for rear view mirror install like a 71. I believe the 69-70 cabs had a different style vent on door pillar and pre-drilled holes above WS frame for mounting rear view mirror. 67-68 cabs had no vent in the door pillar and RV mirror mounted above WS upper frame too - different mounting bracket. Some one can add or correct me if I'm wrong.

If its claimed to be a high end resto - look for aftermarket hardware. That is always a tell sign...

[RenoKeene]

Thats an AC cab alright. My 70 GMC is a factory Big Block 1/2 ton AC truck an doesn't have the holes for the heat shield.

[DANTIP]

Originally Posted by RenoKeene

Thats an AC cab alright. My 70 GMC is a factory Big Block 1/2 ton AC truck an doesn't have the holes for the heat shield.

Next question is when did the heat shield become standard equipment on the Big-Block trucks?

My original question really is "Do the heat shield holes cast much doubt on the originality of the cab?" Remember, A/C does not appear on the SPID but the owner is convinced and is claiming it is original. I personally strongly suspect the cab was changed and the VIN tag was moved to the new cab.

[leddzepp]

Dan- Are you sure those are heat shield holes? They look a little too close to the center....I am thinking the heat shield is further to the side. I do not know for sure, but I will look at my truck later tonight when I get home and see.

I believe the heat shield started in 70 or 71, but not 100% sure.

[special-K]

I'm thinking it must be a BBC cab. I don't have heat shield holes in my '72 K2500 A/C cab. I've never noticed them on any 4wds. The air conditioning would most certainly be on the SPID and if not,the truck didn't come from the factory with A/C.

[LockDoc]

-
Here is a picture from a 72 Big Block truck I am dismantling over at the salvage yard right now. It has factory air and a high hump. It is a 2WD Cheyenne/10

LockDoc

[leddzepp]

Nevermind....Leon's pic saves me from having to look.

Probably a cab swap. It is easy to get rosette rivets off of ebay to reattach a vin plate.

[VA72C10]

So looks to have been put together. What an awesome cab though!!!

[RenoKeene]

I have a heat shield for mine that I got from a board member but it is straight, not bent. Is there a difference from 70 to 72? Don't mean to hi-jack but want to put the correct one on my truck.
Thanks

[Joesjunk]

Those holes should not have been there on a 4x4 cab. But then again, I have seen some odd things happen

[msgross]

My 68 4x4 cab had a factory bench seat and a bucket seat support brace on the bottom.

Always a chance that the factory did "whatever it takes" to build some of our trucks.

[VA72C10]

Originally Posted by msgross

My 68 4x4 cab had a factory bench seat and a bucket seat support brace on the bottom.

Always a chance that the factory did "whatever it takes" to build some of our trucks.

good point....we might not ever know for sure since the cab was blasted....

[HOTFUN]

Dan. Looks pretty convincing to me that this replacement cab started life as a 71-72 big block factory ac Cheyenne cab. It either has a factory tach or the turbo 400 grommet hole knocked out looking just to the right side of the brake cylinder too. I know the tach wire grommet is the top knockout for sure but without looking I believe the turbo 400 electric kickdown wire harness also passes back out from the gas pedal mounted bracket through this or one of those dimpled knockout holes for additional options. I too have also never seen a heat shield on anything but the big block 71 and 72's. Production limitations or mistakes would better be documented with tear down pictures and also is a crucial point when redoing a rare equipped, totally original frame up restoration in my experiences. Super nice cab and nothing that couldn't be corrected to make a "perfect" 100 point restored truck. Mark

[HOTFUN]

Well I need to back track on what that top hole is just to the right of the speedo hole. I looked at 8 different cabs on my place today and there is no rhyme or reason to what was in that top hole if it was drilled. Two trucks had a factory camper harness that a 10 guage red wire came out of that grommet. Another big block had what appeared to be two wires probably emmision relay related. Another 350 cab had nothing, and two had the emmisions full harness coming out and going to the gutter across the engine compartment. But two trucks also had factory installed tachs and one came out second hole and the other the third hole as the brake booster brace about covers the second dimple down. Just some observations. But those two holes in the lower firewall are definitely the big block only heat shield mounts.