Air cleaner Help

[Dirt's72]

I recently purchased a 1972 C30 RV that has original big block 402 motor. The air cleaner had been cut off at the snout after the Thermac control. I'm not sure it is original to the truck, always figured it was. I decided to strip and paint an air cleaner from a 350 small block. I then noticed that the one from the rv on the right side of picture has a much wider snout. I thought that V8 big and small block air cleaners were the same??? If so what could the one on the right be from if it isn't original. Notice the thermostatic vacuum switch is on left on one and right on the other.