Hiya! I just bought a 740GL estate on Friday. It's just what I needed. I've been wanting a Volvo for a few years now, but couldn't justify the costs of running one until we had a baby a few weeks ago and out-grew our Ford Fiesta! (Hurray!!!)
It had to be cheap as my budget is a bit tight. It's in good shape, no damage and no body rot (rust is the big car killer in England), quiet engine, and it had passed the dreaded annual MOT test just 3 weeks ago. I bought it for £250. What I did know though (the reason it was cheap) was that it had done 201000 miles, and there is a whining noise which seems to come form the differential, or it could be the (manual) transmission, or maybe somewhere in between!
The noise starts at around 20mph and is a low whining noise (no vibration), and it builds with speed to an almost unbearable whining and screaching at around 60mph - I haven't pushed it above that. As soon as you let off the throttle, the noise stops instantly. When you apply a bit of throttle again (and the engine takes some load), it starts whining again. The noise is consistent with the road speed, not the engine speed or gear selected.
Any ideas?
Oh yes, one other thing, I checked the transmission and axle oil levels and found that the axle vas very low on oil. I ran the car after I topped it up and found that it is leaking, seems to be coming from a unit of some sort (with cables coming from it!) mounted on the rear of the diff housing just above the filler plug. It doesn't leak much, but I don't know how long it's been like that.
I don't mind getting my hands dirty and doing some major mechanical work, but it's my first Volvo and I'd be very grateful to anyone who can point me in the right direction!

Thanks
ps. Love the website :)