Pennsy: Metrolink is Currently leasing three Sounder trainsets from Seattle, each is six cars. They also are leasing five ACE cars which they use as track geometry and other testbeds, but not revenue (they have the tiny blue Metrolink signs covering up the very visible "A.C.E." symbols on the sides). The Sounder sets are being leased to replaced wreck-damaged cars until the new cars (ETA in two years) come, the ACE cars may have been purchased, I don't know their status...
... ACE and Metrolink ordered cars together, a Co-op order. since ACE was a start-up and success was uncertain, part of the contract for the co-op purchase was that in the event of ACE's failure, Metrolink would purchase the ACE rolling stock, and in the event ACE had a surplus of rolling stock (five sets when they only needed three) Metrolink would purchase the surplus