Thanks to all for the thoughts online and off!
After stewing for a bit, taking out the trusty voltmeter, staring HARD at the ACR battery and thinking about what COULD be inside, I decided to just cut one apart.
After all, while the battery still powered the flash, it WAS 15 years out of date. As frugal as I am (and I AM kinda the crown prince of cheap), I was not going to reuse it.
Upon cutting through the thick plastic shell, I came upon .. two perfectly ordinary Duracell Lithium batteries, available at any camera store for $5.00 a piece!
They were spot welded together and had a bit of silicon seal on either end, but bottom line
, $10.00 worth of ordinary batteries and $65.00 to shrink wrap them!
Guess I'll be keeping these otherwise perfectly good strobes.