Added that one to the list, have seen other 10=5 / 10=6 in 1982, all ST50 base and Spag logo. Looks like that other Spag ET is legit too.
https://www.tokaiforum.com/threads/list-by-1st-body-code.28672/
https://www.tokaiforum.com/threads/list-by-1st-body-code.28672/