No vent?

Conventional spider/damper?

Non-Altec cone with rag surround?

20 Ohm speakers with a DCR of 10? Reconed with 16 Ohm VCs?
I'm not sure that you could tell the difference between the original 20 ohm coils and new 16 ohm coils by the DCR, would be interesting to know the nitty gritty in that respect.