TR6 switch triva mounting screw size

[kengano@advant.com (Gano, Ken)]

Here's a real head scratcher.  The column swiths (Turn and Lights) on a
TR6 use an odd ball mounting screw.  It's very close to U. S. standard
#6 (about 3/8" long) but, after a trip to the specialty fastners
sections, a #6 is to small.  At least the switch will not tighten down
with a #6 and a #8 is clearly to big.

Does anyone know what size and thread pitch a fellow should use here. 
Better yet, anyone got four laying around?

TIA

Ken Gano
kengano@advant.com