Sony TC-399 record play erase heads

I am not really a Sony guy but I had one unit come i with fair heads so I sent them away for relapping, I know you can get these units cheap, but I have some customers that are specific in their requirements

All heads have had a professional relap and come with a head report  and thats  40£ a head normally.

I do not know if these are used in other units as they do not have a number it seems