They used to sell the 1 way (x1 row) crimp housings, but they were discontinued some time ago as far as I can make out. The pin spacing as you have probably worked out for an original 4 way plug (if they were available), should be 5mm---5mm---5mm---7.5mm, the wider spacing of the last pin as a polarising measure is the killer. So I was able to get the last few 1 way housings for my AU-9900, but I also discovered that you could 'make' a 1 way by carefully cutting off 1 way from a larger crimp housing - thus problem solved. So a 4 way can be made up using a 3 way and a 1 way as separate plugs. I hope this answers your question?