I had the recent good fortune to have a part break on an easy road test. Good fortune being that I wasn't on the track / WOT.
The p/n: BPI-CDR Crankshaft Drive Mandrel-drilled for 3 or 4 bolt balancers - 5/8" shaft with pulley for my EVAC system broke off !! The steel shaft that is (or was) welded to the "hub" failed - causing the shaft, pulley, and belt to fall out while I was driving my TA about 40 mph. I found the belt. The hub stayed bolted to the lower crank pulley - but the shaft and pulley bounced off (could'nt find it).
I consider myself lucky that nothing on the car/motor/radiator was damaged. I called Butler this morning about what happened. They said that they have had some failures with these pulley/shaft/hub assemblies and that they can replace it free of charge. However they did not have any in stock? I told them I needed something over nighted - because I'm leaving for Pontiacs In The Park this Thursday ! He said he'd see what can be done??
This was the kit that I bought last spring:

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