This string of questions came about because the little piece of plastic on my brake proportioning valve blew out and I lost my brakes while driving.
Here's my long list of questing and any info would be greatly appreciated:

We're there different brake set ups in the engine bay (different types of boosters or master cylinders used depending on version)?

Since I can't seem to find a replacement proportioning valve, is there an alternative to the stock one?

Is there an upgrade that people do that would modernize the whole brake assembly?

Or any other info that might help me get my brakes working once again?

 

wreckers, or place a wanted ad in here or jeep recycler

never heard of that issue before

Have you checked Rock Auto

 

There are 5, according to MoparPartsGiant.com but they only have '94-96 & '97-98, the others are unobtainable. If you're lucky & yours is one of those years, they're not cheap. RA may be a better bet, they specialise in ends of lines & suchlike. A yard still seems the best bet because, chances are, you don't need the whole thing.