Quick sidenote: sorry if it appears to be a thread jacking.
There are massive differences in depth...condensed version.

10W7 has an 8" mounting depth while the
10W6V2 has a 6.9" mounting depth and the
10W3V2 (W3 are discontinued and the voice coils on the two's don't fry at accidental over-wattage like the first series) have a 5.75" mounting depth.

Here's a good reference example. The MTX Thunder 5500, a quite decent sub if installed and used correctly, has 6.158" mounting depth. It doesn't sound like much but it is, one inch is almost one full click on the seat track. It adds up quickly, especially if installer/builder becomes overzealous with the box.

 

Texas Is giving extremly good info here. I know I lost a little more leg room with my set up than I expected (still livable). I had an inch and 1/2 i could have used to make the box shorter. 1/2 an inch would make a great difference for me.

 

Thanks for the compliment...
The RE8s play very low and have some amazing output. I had two in my truck before and with 4 now I have plenty of headroom. Unfortunately you missed out on a group buy going on at another forum on RE Audio products... they were selling for a mere $37.

4 RE8s should get louder than 2 10s and will require less airspace and have shallow mounting depth.

 

thanks, im aobut to make a new topic with some ideas i have right now..