AMD Golf Cart Motor GL0-4001 series motor. These are nicknamed "the beast" online. 

Check online for pricing: Amazon has this exact motor listed for $600+$76 for shipping. I bought this for an older cart but ended up selling the cart without using this motor. It's in great shape, literally brand new from EV drives. Been sitting on a shelf for about a month. 

8 HP, 1600 RPM at 36V

11 HP, 2300 RPM at 48V