Your right there aren't "lifter's" The rocker arms ride the camshaft pushing the valve down into the head. You'd actually be adjusting the valve clearance between rocker arm & valve assy.(valve/retainer/keepers/spring) That should be done about every 30,000 miles while the engine is cool.
Its hard to say what the noise is that your hearing, without actually hearing it. It could be the throw-out bearing, but chances are its an internal bearing like the input shaft bearing. If thats the case, instead of wasting time/money rebuilding your trans a rebuilt would be better & only like $300(not including shipping)
http://www.binghamtonlife.com/manual/2gsm/default.htm