If the original sub was ported (and i think it was), then any driver going in that box will be a crap shoot. It is best to stick with the original driver... Otherwise the sound will most likely be way off.
if it is a 4 ohm, the swr12d2 (wired in series for 4 ohms) and the tcsounds epic 12 (also dual 2 ohm coils, so wire in series for 4 ohms) both have around 20mm or so xmax. the swr street price is about $150 or so and the epic 12 is just under $200.
"Ok I found some info on the idmax and found out they have decent output till about 15hz"
they have about 25mm xmax so about 2db more spl than the other 2 drivers mentioned.
saying a driver has output till 15hz is meaningless. every driver has output at 15hz. the question is how loud. in the low frequencies excursion limits spl, so just look at excursion if you want to know how low a driver can play.
Either would be fine, the biggest question mark is what the amp can do,and what filters are designed into it. You may have a subsonic on it that rolls everything off at 20hz anyway. I would fist be concerned about matching or besting the old drivers sensitivity because if even if you have a capable driver, you still need the power behind it. I think any of the 3 or 4 mentioned here are great, also Dayton brand has some great choices for a solid price.
ok so the asw wont fit where i need it to so i am going to move it to the real and ut a idmax 12 in it (to keep all the drivers the same).
i will put each idmax 10 in 1.3 cubic sq ft of space and run a total of 4 for my front stage (purchase 2 more).
here are pics of the front stage layout to help you guys understand my situation. Also put a pic of a car sub box to help get a visual of what i want to do.
one other option i was thinking of is 2idmax 10s for 50hz down and 2 id10s for up till 250hz.