I believe this to be most similar to the OKUMA A118-8435 or the HAAS HSL30-8435 tooling block.
Based on my research, this tool block may fit the following brands and machines as they have the same bolt hole pattern:
Okuma: Cadet, Captain 370, ESL8, ESL10, Heritage LB-15, LB15IIM, LB250T, LU25, LU15, Crown LB25, CAP470, L1420, LB4000EXBB/1500, L470, Genos250-V8
Haas: SL20, SL30, ST30, ST31, TL15, TL25