i couldn't imagine that you'd find anyone with the exact template of the golf-carts you're about to wrap, if anyone had one up for grabs to begin with.
just figure you'll need x.amount of time to to draw it up yourself, and work it into your pricing as a "setup fee"... couldn't be more than a few rectangles'-worth of canvas area anways, and you can mark-up your sale with something and your client justifies the expense by spreading the cost over the 6 carts being done.
I just made one up in 5min., but a proper survey on your part should make the job pretty simple: