My engine guy down in Tampa has built a 383 for a guy. He bought some Pro Comp rockers for the 383 for around $150 or something. The adjusters had problems (not drilled right from what I can remember) and the counterbore for the jam nut was not perpendicular to the centerline of the threads. It cost more to buy quality adjusters than the original cost of the rockers, then added to making a fixture to machine the c'bore/spot face for the nuts. He called the supplier (I think in LA somewhere) and they couldn't tell him where they were made or who made them. It sounded like they bought a pile of parts (Alibaba?) and were just selling them off.