Alternators, who runs what?

I have had about 4 alternators go bad on my valiant.
They either fall apart on the inside or start sparking with rpm and the + post.

All from autozone.

"Remanufactured" parts are almost all junk. Those from Autozone and other "Davey Do-It-Yerselfer" types of places are especially craptacular. Yeah, they come with a lifetime warranty...which means you get to spend your lifetime replacing their cruddy thrown-together parts.

I've been thinking about a denso unit and some fabbed brakets.

You could certainly do that; the Denso alternators are really nice (lightweight, reliable, and they give better low-RPM output than the Chrysler alternators). However, keep in mind you will need to have a thought for the ammeter in the dash if you upgrade the alternator. No, I am not one of those (like the Chevy-headed yutzes who run the MADelectrical site) who run around squawking like headless chickens, claiming you have to convert to a voltmeter right now, today, this instant or else you're going to burn your car down even with a stock alternator...because that's not true. A realistic, technically-correct discussion of the situation (from someone with extensive experience with Mopar systems) is presented here and there's additional discussion and links here.

I may go to a Denso alternator myself eventually on my '73, but for now I just did it the easy way: got a new (not "remanufactured") Chrysler alternator from Old Car Parts Northwest.