1975 904 for slant 6

Appreciate you but not buying used converter. Theyre to cheap to take a risk of doing all the work to Put on in and doesn't work right . Thank you 1500-1800 ish is them what I'm looking for . Any idea what diameter is ? Rock auto doesn't even have listed nor any parts stores . They all show the 727 converter as the option and I know they are not the same