1972 3/4 t0n 4x4 Ambulance?

[Sir_Burban]

Alright, I recently purchased a low miles ambulance/suburban out of Colorado. Here's the thing, the company that fitted the top was out of Indiana, and doesn't exist anymore, and the truck is showing a VIN code C/10, so, I know that a small number of public service vehicles were purchased 1/2 ton and then out-fitted with heavier springs/axel's. What companies were available, or how do I get more information? any tips are much appreciated, thanks.[ATTACH][ATTACH][ATTACH][/ATTACH][/ATTACH][/ATTACH]