After successful surgery I can report that:
the comp driver is labeled 2418H and is NOT listed on the technical library of EVERY driver JBL ever made.
the horn has no label and measures 12 3/4X6 1/8 and appears to be a 90X40 degree, like the 2373 but not listed as such. The 2373 is wider.the woofer is labeled M115-8 but no such listing exists on the list of every driver ..... but there is an MI-15 bass guitar speaker whose Thiele-Small does show up on the site and is in Boxplot and WinISD. This 15" woof is a lightweight.
If I had spent 300 or 400 for each system I would have refused it as not being the 3677 but rather the 3677s (for surround). However, at $118 each, I should be able to build a kick-ass theatre main with the woofs in the 4648a-8.
The good news is that the 4648 has the 2226J woofer as advertised. So the 2 woofs from the 4648 and the 2 tweets from the 3677s, while not the exact Pi Profesional components, should turn out to be pretty good for the $450 invested.
Funny thing: the mystery component 3677 cabinet is a work of art with plastic vents, nicely done bracing and acoustic material. The much more expensive 4648 has paper vents, looks thrown together and the black paint overspray covers the damping probably reducing it's efectiveness. I wish I had a bass guitar to try on it, though!
I think I will try to get a V.P. from JBL on the phone and give him/her the liar-liar pants on fire treatment. Shameful!
Comrade Wayne, have you ever heard of the 2418H driver and 23something-something horn?