I was able to find a diapragm and kevlar disc at South Bend Clutch in South Bend, In. I've also dealt with Fort Wayne Clutch and they're also very good. The diapragm is a little easier to use on the street and it still has enough gripping power to run 13's @ over 100 mph.  

Frank/Rebop

Bristol, In ( by Elkhart) 

If you still have the 1 3/8 10 spline, you are out of luck for any off the shelf performance clutch.  In fact, for some reason a stock clutch seems hard to find.  I finally found a stock replacement at Carolina Clutch.  It seems to be doing well with my moderately modified 292.

If you've swapped to a different transmission you may be in luck.

          Diaphram? Long style, ????

                 Truck will go to the strip every now and then, but mostly

          street use.                        Thx Bill

Bill

Pelham,Al