After months of design and modification with inputs from @b264 and @pixelsilva, here are the Evolve GT motor mounts we came up with:
Specs:
8mm thick T6061
Fits wheels up to 107mm (can be custom to fit larger wheels)
Dual idlers with standard size sk8 bearings
All stainless hardware
Inside, under the deck or rearward, outside facing motor mounts
Top: outside facing
Bottom: inside facing
Parallel slots to fit either 63xx or 50xx motor and elevate ~20 degree from the ground.
Universal motor mount with motor protection with the extended lip. Can also be outfitted with rear rubber bumper (2 threaded holes toward the rear) for additional motor protection.
Dual - inside mounts
These mounts are designed to fit wheel sizes up to 107mm. I would need to modify the mount to fit AT kit. The price for the motor mounts (2) is $150 including US shipping. Pulleys are sold separately, ranges from $20 to $50 depending on the # of teeth.
They will fit dual 6374s. The Turnigy sk3 “6374” are not 6374s, despite their name, more like 5984 and that’s why they won’t fit. There is room for 75.5mm of motor