that's an expensive part and if you find a rebuilder i REALLY want to hear about it. so far the only cheaper fix i have found is an hei distributor with vac advance and an air governor. have seen several retro's but have not done one myself. they seem to work very well but emission control would be comprimised.

to clarify the issue further, the machine would crank but not start due to no spark. if you disconnect the 4 pin connector on the Dist, it would spark and run briefly, the controller cuts off the fuel supply if it does not get some feed back from the dist.
I replaced the ign. module, the sensing coil. and Ign coil. Ohmed out every wire. No Joy....
I sent the electronic govenor/ ECM off to have tested, initally it worked fine, but after a couple of starts it duplicated my problem on a different machine.
Soooooo. it was a computer fault, i am now waiting to see if I can get it rebuilt, a rebuild to replace it or a new one..
Thanks for your assistance.

I went through the same thing with a Toyota with the 4.3 and it turned out to be the ignition module. Drop by NAPA or Lordco and pick one up. It's only $60.

Thanx Toyzilla

I will try that, as it seems odd. I drove it to the service area to set up the throttle and limits and when I finished it would not start.
So, everything helps.

put a second ground cable from the battery to the engine (alt bracket works good). dont disregard this advice, it's cheap and if you try it you will see results. you can do a voltage drop test first if you like. from battery to engine meter on d/c volts in crank mode.3volts or more is too much.