I need to replace on of the these on my 67 912. I've found somewhere to supply them but need to supply them

The diameter of the UJ's caps or shafts that fit in. Normally 15 or 16mm I've been told.

The span of the UJ. Normally 38 or 40 mm I've been told.

Thanks for you help.

Of course if you have one for sale please lot me know too.