Mars22

I just bought a 1999 GS300, 264K miles, its been pretty well maintained BUT its got a clunk from the driveline when you press the gas pedal, it doesn't do it every time, but if you are cruising along at like 40-50mph and press the gas and let off and press it again it will make a clunk. I am thinking it may be the center driveshaft bearing, maybe a ujoint going bad(are those replaceable?), the guibo/flexdisks look okay(but are they really $150 a piece? Seems pricey). Any help would be appreciated because I just don't want to start shotgunning parts at this thing.