Original 40 Ford would not have originally had a 10-inch. (As flatjack9 has said)
'Course, you didn't say if it's a 40 truck... that might make a difference.
So, I assume you are looking for a 46-48 flywheel (car) which would normally be 10-inch. Or, as flathack9 posted, a 9-inch from 40 and earlier.
For whatever it's worth (and I'm only offering, not placing an ad), I have an unused 46-48, 10-inch flywheel and fresh clutch, from a project that I abandoned. Flywheel has been surfaced and balanced. All work done by Clutch Masters, Rialto, CA.
And, I also have a 40 (and earlier) flywheel for 9-inch. This one is 'as was', not resurfaced or balanced.