Altec 16" 515B versus 515C. ID questions

[Elitopus1]

I have a single 16" 515b frame. I have been looking for a mate for it. The plan is to send them both to GPA for a recone/recharge.

This 515 popped up on ebay today.

Vintage ALTEC LANSING 515C Voice of the Theater | eBay

The seller claims its a 515c. He also says some BS about being rear vented like a 421.
I have seen some 515 with this hole in the magnet cover but still don't quite know why its there. Thats not my issue.

Anyways, my question is related to the magnet cover. It has been my experience that the 515B have a magnet cover like this. Notice the ridge around the edge.



It has been my experince that a 515C has a magnet cover like this. Notice the smooth, curved edge. I would assume they slightly changed the motor assembly for the 515C. Maybe its just cosmetic. Who knows.



My point is I think the woofer in the listing is really a 515B. Can anyone confirm this?

[mah]

Earlier enquiry: Odd bod rear vented '515B' - note the warning re. the metal disc covering the rear vent.

[Elitopus1]

Thanks for posting the link Mah. So it looks like that is in fact an early 515C. Must have been before they switched over to the different style magnet cover.

Oh well, the guy wanted too much money anyways. I'll continue waiting for a 16" 515B frame/motor to show up.

Thanks