The factory 5 speed ZJs are pretty rare. I'm not saying you couldn't find one in a JY, but here's where I'd start:
and do a search using these parameters:
Jeep Grand Cherokee
Leave the area blank for the widest search.
On the next page use "Non-Interchange search using only Jeep Grand Cherokee"
Select year range 1993-1994 (The only model years the 5 speed was sold.)
You'll get a whole page of results ranging in price from $25 to $75. Ignore any that say they are from a 5.2 because those weren't made with a 5 speed. Start calling the others and ask if it's actually a brake/clutch pedal assy from a manual or just a brake pedal assy from an automatic.