Is there anything in the engine of a car that would make a winding down/whirring/spinning sound when the clutch was engaged? I can't think of anything so I'm hopeful that it isn't in the engine, probably isn't in the tranny, and is most likely one of the two bearings (pilot/throwout).

I checked my tranny mount and it needs to be replaced anyway so I might as well pull the whole thing out, regasket the tranny and put in the two bearings and the rear oil seal. I'm hoping that the new trans mount will alleviate the problem I have with the tranny jumping out of 4th when I take the load off - but if not, is there an adjustment that can be made to the transmission that might take care of the problem? (to recap: if I am in 4th (or o/D it makes no difference) and I let off the gas suddenly, the transmission will pop up out of 4th into neutral (or to a half-way point between engaged in 4th and neutral). I can't force the gearshift out of 4th by trying to push it out - even if I try to push it out of 4th without engaging the clutch it won't come out of gear. It only comes out of 4th if I let up off the gas. I don't notice any gearshift wobble.