I bought a new chuck for my lathe and it came with a D1-6 adapter for a flat back chuck. I needed a D1-5 adapter (chuck was a good deal) I bought a D1-5 adapter for my lathe, fitted it to the chuck and "bobs yer uncle". Now I have a D1-6 chuck adapter for a 8" chuck. Complete with studs and timing screws. New never fitted. Came with a Yuasa Chuck so I expect it's a Yuasa. 125.00 and I'll pay the USPS Flat rate box shipping in the lower 48, won't ship outside lower 48.