It wasn't a joint. It was just an edge of the coil. The insulating material wasn't correctly placed squarely under the coil, so the sparks found a path to the frame.
The controller was a Curtis, upgraded to 1000 amps. It probably didn't help the short, and might have not have blown if not for the short. I'll never know. I have my Zilla installed now, motor not shorted using A/C motor tape we use at Coca-Cola when repairing A/C motors. Probably the same stuff.
Trucks running fine, nothing more to tackle. Well... other than the MiniBMS's I blew when trying to wire up the circuits that shut off my charger. One of the relayed wires touched the pack, sparked and now there's more smoke getting let out of the boards. The relays show high ohms on several boards, and the end board's buzzer is on constantly.
Whatever, the charger is set to turn off when the pack is full. I might have to install my WICOM BMS sooner than I wanted. Just involves removing some panels on the side of the battery pack, and a crapload of wiring!