[RichardJ]

Before I added the AC, I had lost two balancers. The first one lost the outer ring while driving down the fwy. On the next one the ring dropped to the ground when I started the engine.
I found a single pulley to bolt on the front of the hub to trap the balancer ring and keep it from flying off. later it became the AC pulley. Witness marks painted across the outer pulley and the balancer lets me know if the balancer ring has come loose and slipped.

When looking in the wrecking yards, don't forget to look at '70s X-Body Nova, Apollo, Omega and Ventura. many of those had the 250 six and are a good source for the pulleys, brackets and 6 cyl HEI.