75-87 Chevy Extended cab pickup

I know for a fact from the reserch I have done over the last 12 years that neither Chevorlet or GMC made a fullsize extended cab pickup in the 75-87 body style can anyone tell me the company that manufactured these custom ordered trucks, all I know from what I have found is that there was one and it was in Texas, and weather or not the company still exists.   the reason I need to know is because I intend to make my own by cutting down a crew cab from a 86 and grafting the rear half of the crew cab's frame (it's a 2 wheel drive) to the front half of a 79 GMC High Sierria 35 4x4 and boxing the whole thing out and I was going to attempt to contact the company if it still exists and get the spec sheats or possably a basic print so I can build mine as a clone to the ones they made, and also possably get the windows for the extended cab from them f they happen to have any NOS.  
It's NOT what you buy, It's what you Build so build it big or leave it on the trailer