I found an old M&K MX70 on eBay that has 2 8" woofer sin a push pull configuration, unfortunately, the surrounds were bad and after re-coning, the woofers were severely outdated. I needed 8 ohm drivers that had close T&S parameters and this fit the bill. Wired each sub for 8 ohms and swapped out the stock woofers. I was VERY pleasantly surprised how good they sound and even had to reduce the insulation because these need less space than the stock units.
I have a pair of Magnepans that are very revealing AND fast. It is very hard to find subwoofers to match it’s speed. M&K’s are one of the few that can do that. After replacing the tired Capacitors on the amp plate, the sub is better than new and can definitely go LOUDER. And because it is a sealed unit, it is very tight and controlled.