I have been trying to remove my crank pulley on my 75 280 and at the point where I install a puller to remove the pulley (mine has two).  I can not determine what the thread/pitch

of the holes in the pulley. It seems like a 6 mm and starts to thread in both holes, but stops after a couple of threads. Does anyone know what this bolt size is ?

Thanks in advance.....Ron

BTW the major bolt in the photo has been removed.

M6x1.0 bolts. IIRC You will only get 4 or 5 turns into the pulley before it bottoms out against the timing chain cover.