[racerx78]

Originally Posted by bsbabcock

Parts Expressayton QT210-4 8" Quatro Subwoofer 4 Ohm

Also, one of these kicker ssmb8's was mentioned.. I wish I could find that thread now.. it's old.
Kicker SSMB8 SS Series 8" midbass speakers at Crutchfield.com

Also Hybrid Audio just came out with some 8" mid-basses that might fit the bill.

Also.. maybe something like this Peerless SLS, if it fits..
SLS 830667 Peerless 8" Paper Cone Woofer from Madisound

It's almost like rolling the dice to see if the driver can be crammed in there.

I found the MTX 4500 series is supposed to be a free air subwoofer. it could work nicely and its not expensive.