Hey~ Sorry for response lag, I haven't been on here in a long time - too many other projects so the truck (and forum) has gone to back burner. The only place I've run across that seems to carry parts for the larger F4-F8 trucks is Job Lot Automotive out of NY.
JobLot Automotive
My truck came with a sb chevy conversion to the original trans, not sure what the clutch was in it. All have been pulled in favor of a later model Ford eng/trans.