MotorcycleFool

I went to look at an '88 Ranger GT the other day. It ran and drove great (74K mi.), except that in 5th gear it has a REALLY irritating buzz/whine coming from the transmission. It sounds like a bearing 'singing'. I only drove the truck about a mile up the road and back (no tag or inspection), but the noise seemed to be consistent in 5th, with no real change with road speed. I had it up to about 60, I guess.

It doesn't go away under any circumstances (power on/off, pressure on gearshift, etc.) It makes the same zzzzzzzt noise for a split second when it's being upshifted into 3rd and 4th, but as soon as everything's properly engaged, the noise stops. It's only a split second in either case. The noise doesn't come back in 3rd or 4th. It's constant in 5th.

It has a 2.9 V6 in it, if that makes any difference. Anyone have any ideas (from experience, please, not conjecture) on what the problem might be and what it might take to fix it? Thanks in advance to anyone who can shed any light on this situation!

P.S. I won't be back on until tomorrow afternoon/evening.