I'm starting to suspect that either the Designed2Drive plate as it is now isn't an ample enough heatsink - or the placement outside the distributor behind the block accelerates the failure
-Kurt
I doubt heat sink is the issue. Actually CHECK your running voltage and see what it is for starters. It's possible the coil has a problem, but works well enough to still run. I didn't even USE a heat sink. On my 67, I mounted the thing (as an experiment) on a flat area of the firewall above the dist. below the wiper motor. Someone had drilled a hole there so I just drilled one more and screwed it on there. Separate ground wire. Make sure your modules are mounting good and flat on the plate, and does it have the hole for the "peg" sticking out?