I don't know the answer to your question, but I would think that if you are certain both motors are 235, and you have your years correct, the smaller balancer would fit on either motor. People did strange things to these old trucks when they were being used regularlly. Anything that would work, and keep it running was the attitude. It didn't need to be pretty.
My guess, and that's all it is, is that at some point, someone needed a balancer, had the monster one on hand, found it would fit, and put it on. Lord only knows what it came off of. It must have worked, and that is all they cared about. Allen
