So it's getting really tough to switch gears, especially 4th and 5th gear. I've always had to push a little harder on these two but the problem has been getting worse. I replaced the slave cylinder and master in December and I knew I should have replaced the clutch while I was already right there. My question is what is a good clutch kit to get? Should I get a self adjusting one? I need one with a pilot bearing for sure. And what else will I need going into this job? This is going to be the first clutch I've ever swaped out. Also, why do all these clutch kits have different diameters for the same year model? Thank yall!

Hydraulically operated clutches (slave & master cylinder) are self-adjusting, to my knowledge.
I have heard good about LUK clutches, but *know* nothing as I have not had to replace one yet so have zero experience.
I would check the sponsor site, if applicable, and rock auto... even Amazon & ebay. Once you find a 'kit' you are interested in, do NOT take the 'application list' as Bible. Get the part numbers, and check their cross the the FoMoCo parts numbers listed. Too dang many variables of engine & transmission to just take 'one from column A...' without checking.
tom