What comes to mind is the size of the fuel tank.I would look up other Dodge trucks with the same size tank and maybe gain some information from that. I had a K-5 Blazer
once and had a difficult time getting motor mounts. Finally a sharp parts counter guy said that during that model year they built that vehicle AND certain catering truck type
vehicles on the same chassis, so next time i ordered parts i ordered them using that information....who knew...
I mention this because sometimes we need to look a little past what we have. A motorhome starts with a bare chassis, drivable, so there's a fuel tank on it. What else could
they use that chassis for, maybe a shuttle bus? That may give you another idea of what to look up.........