Thanks for the advice. I wrote them an email and they said the company split in the 70's (heads production and transformers production) so they don't have much documentation about the transformers anymore.
They sent me the only document they. I'm not an expert and struggling to read electronic specs, if someone can explain them would be lovely! Thank you
Maybe im wrong, but this looks like: For 150R legs 1-4 input join 1-2/3-4, and join 6-7/8-9 for 150R output legs 6-9.
500R join 2-3 input on legs 1-4, 500R join 7-8 output on legs 6-9...