How interchangeable are 318 harmonic balancers?

Thank you for the responses.

Last night I took the middle-of-three spacers and opened-up the oddly-shaped spaces between the holes (see my picture above). Then I installed six studs in the new balancer to see if this "opened-up" spacer would fit over the studs, and it works!

I'll open-up the other two spacers, and "massage" the pulleys, this weekend sometime.

Thanks again.

Jim