I think Walcks, kaiserwillys carries the current reproductions, willysjeepparts.com may have NOS and NOS turns up from time to time on ebay. Northwesternautosupply in MI might have NOS too.
Egge produces them without the heat dam groove near the top and uses what they described to me as a "modernized ring pack" to eliminate it. The top of their piston is also turned a few thousandths smaller than bore size, my machinist said he thought both changes were an improvement over the old design.
