Anyone know the correct core height? Aftermarkets are listed at 15 1/2". Might the originals have been 16"?

Jim,
I replied to your email. I measured 16 inches; bottom of top tank to top of bottom tank, where the tubes enter. The distance between the flanges that solder to the tanks measures less (15 1/2 inches).
Bruce

Mine is also 16" bottom of top to top of bottom.

Thanks much guys.