Pts Coilovers- Different Threads?

[philfingers 5]

I picked up some s/h PTS coilover parts recently. However only the one lower spring pan is the correct fit for my genuine PTS bodies. The other lower spring pan (which looks identical other than the thread) and the two locking rings are very slightly finer thread. Is it possible that these are earlier spec ones? They look the same only on close us the thread is slightly finer. . . .

I think the one which fits my current PTS bodies is ~M50 x 1.5

the fine thread is ~M51(?) x 1.0

[philfingers 5]

some one must know! maybe they're Escort or Sunbeam? Definatley 70mm ID springs tho. The fine thread may well be 2.0" 26TPI?