Hope I'm right in thinking modern FB means post war and not just new FB's as recently marketed.
A real head scrather - 6mm threads!!
Would appreciate some expert advice
Much against better advice I took on this neglected model 95. When working on these old bikes it's always a nightmare checking and fixing botched threads. There are so many variations of imperial threads, but this AMC 150 has me scratching my head.
There are 5 screws securing the inner primary chaincase. I have several crancase halves into which foilk have tried 1/4 bsf and 1/4 cycle. I have one unmolested crankcase half with original screws which, and this is where I'm bowled over are the from what I have checked are 6mm threads See pictures