[HEI451]

From info on this, and the 6066 sites, I am led to understand that the larger series trucks that had the V6's, C40, C50 and C60, had the factory tach in the dash. I haven't run across one of these trucks yet, but I am always looking.

The only other way to get the factory look would be expensive, in that a stock V8 tach would need to be obtained, and the movement behind the facia would need to be changed, to an aftermarket one, to make it all work with the V6.

The aftermarket tachs that are for 4/6/8 use a series of resistors to change the signal input, and changing the number of resistors sets the signal for the different number of cylinders. Some tachs use soldered in resistors that must be cut to change the signal, others use a rotating switch and resistors built into the printed circuit of the tach.

I'm still researching the whole mess, but, if a stock facia could be obtained for the tach in the pictures above, that just might be the best and easiest way to get a stock look tach for our V6's. The facia on a stock tach is silk screened in with ink, usually water soluble. but, a clever graphics person, or possibly computer program, could reproduce the correct facia "decal/sticker", and a simple aluminum or steel thin sheet could be cut into the correct backing plate, and mounted to the aftermarket tach.

Complicated, but not that complicated.