Attention to mounting of JBL drivers!
The cabinets designed for Altec drivers were usually mounted behind the front baffle board. Altec drivers have a mounting flange that is rather WIDE which means if you mount a JBL driver the same way you will encounter the surrounds slapping the front baffle board.
Altec drivers measured at 16" have around 13 7/8" actual cone/surround area, JBL drivers have a very NARROW mounting flange(meaning more actual cone area for the same "published" size driver vs the Altecs). I found this out by accident while using a JBL 2226 in a Altec A8 enclosure originally made for a Altec 416 driver.
I now measure instead of guessing or assuming!
Ron