I don't know about clutch brands, mine came with the truck. All I had to do was put it in, (what a pain).
As for the 5-spd. It will bolt right up to the engine, but I've heard you have to manufacture some stuff to make it really work. Including: new shifter hole, new tranny mount, e-brake bracket, and a shortened rear driveline, cause the 5-spd is just a few inches longer. If you're still interested I'm sure someone here can fill you in on more details or point you to a thread, cause believe me, it's been talked about alot.
Welcome to the sight and happy Luvin'
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Richard Barnes Salt Lake, Utah
1980 Luv Mikado 4X4
http://geocities.com/luvtruck2004/