Turns out there is no problem with the alternator. When Adam said he couldn't start the Mach we assumed the battery was dead. That was not the case. I got in it over the weekend, hit the key and it clicked. I hit the key again and it started right up. Must be a connection problem some place, although it's started ok since. Will have to check it out.

Sure you got a full charge? Also could just be a dodgy ignition switch or a combo. My vette does this frequently when the battery is a little low, but never when fully charged (right off the charger at 100%).

Is it just clicking the starter like it did with the bad battery or is it doing something different?

It did not have the continuous click like with the bad battery. It clicked once, I released the key, hit it again and it started right up. Have not had the problem again - so far.

It could be because of the dual solenoids or that the old one is going bad. Remember that the new starter has a solenoid on it and that the instructions showed us to wire from the original to the new. If it happens again I check the old solenoid and the old wiring going to that solenoid. The wiring going from the old one to the new one shouldn't be an issue since I mounted it in the heat shield and routed it to the oil pan away from the exhaust but you can double check it as well.

How's the Mach running?