is there anywhere that 2 10's would fit in a '93 standard cab?

 

Yes and no. Depending how big good you want these subs to be.

You would probably be best to get a hold of a couple Bazooka 10" Tube subs off e-bay or somewhere. I don't think there is much room behind the seats in a 93, so the tubes are your best option.

Otherwise, you could buy seperate subs and have a custom box ordered that will hold them, as long as the mounting depths and air volumes are acceptable in the box.
I could only fit a single 10" into my '00 reg cab, but then it's an SPL sub with a mounting depth over 6" deep and requiring at 1 cubic foot of volume in the box.

 

You can easily find 8s with a mounting depth of 4 inches, meaning you could have a 6.5 wide box propablly, take some measurements behind the seat, and see what you can work up.

 

Also Rockford has the new shallow mount p3 10" subs that may fit where you need. And don't forget if you can't fit 2 subs you can always make up volume with more power.

 

Pioneer has some 10's and 12's with < 4" mounting depth, might also be worth a look.