has been running rough and finally lost the ignition module...and it wouldnt do anything. no power to cab, ignition, etc... replaced the module and the black box under the dash (cruise control box?) because it smoked a resistor and blew a capacitor... truck ran like it never has before for about 200miles... and all of a sudden 60mph in 4th gear i get a wicked backfire... and the tach drops dead... and i lose fire to plugs... deaed in the water... another blown ignition module? if so... what is blowing them?

 

Are you saying new ignition & possibly cruise control modules fixed your problem of no power to the cab? Black box under the dash could be many things; pictures are good, FomoCo part numbers are ideal

What is the status right now concerning power to the cab/headlights/etc.?

 

i still seem to have power to everything else in the truck... windows, lights, starter... the rest of my dash is working.. tach is dead... not even the slight bump when im cranking on it...
all my fuses test good.. have 12 v to 1 side of coil with ignition on.. but i dont seem to see signal going to the other side.

 

just went out and checked the old ignition module... same results... power to everything except tach... and no spark... the ppl i got the ignition module from are sending me a new one in the mail tomaro morning... hopefully i just got a bad egg...?

 

It sounds like you need a new coil.

The tachometer reads the RPM off of the green wire of the coil in pulses, each time a cylinder fires. No tachometer reading but everything else works tells me it's probably your coil.