[Motorola] Lowband Syntor X

[Geoff Fors]

I presume you are referring to a Systems 90*S style head?

The small blue plug which looks like the mic plug goes on the far right of 
the lower row as you face the rear of the head.

A typical main head w/o option boxes would look like, when viewed from the 
rear:

Top left: Violet plug
Top right: Gray plug
Bottom left: Black plug
Bottom middle:  Mic
Bottom right of middle: spkr
Bottom far right: Blue plug

The plugs are keyed so that it shouldn't be possible to put them in the 
wrong holes anyway, although I think as you say, the mic and blue may fit 
each other's sockets.

Geoff
WB6NVH