In general you're SOL, and with GE, in particular, you're SOL.
The good news is that you aren't the first guy to have had to make his own parts. The bad news is, I would not reccomend this unless you have the engineering / testing lab experience to support you, and know the particular standards well. After all, it's your tail out there.
BTW, the insulator is usually an expoxy resin saturated fiberglass. Check wiht plastic supply houses; chances are they can get you the right stuff.