[thundus]

I'm looking at a '72 911T for purchase. During test drive, car makes a dragging type noise, directly related to vehicle speed (frequency increases with speed, no noise at stop), in 2nd gear only. Noise is exactly the same regardless of clutch engaged or disengaged, and does not change with engine load; noise goes away as soon as you pull lever out of 2nd, and comes back (with vehicle rolling) as soon as you pull it in. It's the kind of noise I'd associate with a differential or dragging brake pad, but since it's so obviously tied to gear it must be in the transmission. Noise level is high enough that you can't miss it with windows up, top on, radio off (both my wife and I caught it in less than 5 miles of driving), but not so loud that it couldn't be tolerated. Transmission otherwise operates nicely, syncros seem fine and no gear noise.
I don't know much about transmission internals generally, and nothing about 915 internals specifically... any theories on what this could be, and if so, is it an issue to drive the car with the concern for the summer and put off transmission rebuild until the winter, or could this be putting metal in the case and cause further damage? If this is specific to some 2nd gear bearing, is there any such thing as a partial/cheap rebuild or assume costs for a complete?
Any info greatly appreciated-- I really want the car but need to make sure I can afford the repair expenses...
Thanks--