Paul,
I don't have any idea what part of "down unda" you're located. However, if you find bertsmobile here in the forum, I'm going to bet he can help you out and may just have a clutch in stock that can be fit to your old Hustler. Also, bert is Tha Man here in the forum. If he says it, put your money on bert.
I'll also see if I can find you a source.
Welcome to the forum and good luck,
Max