I have 2 Furys here at the moment, my uncle has the other. One might have a 10 amp motor. Two were bought new at Ames back in the day, the other I hackjobbed from a couple I garbage picked. I had another hackjobbed one I sold to a coworker who as far as I know still has it. I know I used a 10 amp base to make the one my coworker ended up with.
There really isn't a lot of difference between the 10 and 12 amp in terms of performance. Was probably more marketing to sell the Thunder.
FYI non abrasive liquid car wax shines these things up like new.
On a side note I don't know why they'd want to sell Thunders over the Fury, it had twice as many parts (by my estimation, probably really does), probably cost more to make. They could easily have made more selling the Fury instead, lower parts count easier to disassemble/assemble.