I don't know where you are, but I know of a shop in S.E. Indiana that has an informal boneyard of mostly Yamaha carts. I've found "hard to find" body parts there in the past. Might be worth checking out.
Quality Carts 7307 St Rd 46 E Batesville, IN 47006 (812) 933-1400
http://golfcartdude.com/