Good evening gents! I just bought my first truck and need help on the diagnosis, here's the details:

• 1990 Dodge Dakota, regular cab, long box
• 3.9L V6
• Auto trans (4 speed, previous owner rebuilt at 100k and added a shift kit)
• 4WD
• 156k miles

The craigslist ad said it had a tranny problem, when I talked to him he said he thought it was the torque converter because it shudders and sometimes stalls when in gear and stopped.

So we let it warm up before the test drive and it really seemed pretty ok, it was just in the <10 mph range that it shimmied a little and we had to pop it in neutral if we had to stop to keep it happy. I was comfortable with a tranny problem for the price so on down the road we went. I had trouble still at first getting from his place to the highway, but as long as I didn't stop all the way without popping it in neutral it was fine.
On the highway I noticed that there was a whirring noise coming from the front of the truck. It was

• Speed dependent: it only happens over like 35 mph.
• RPM dependent: it gets higher pitched the higher the RPM.
• Throttle dependent: it stops when I let of the gas.
• NOT steering direction dependent: happens all the time, turning either way or straight
• NOT drive dependent: checked in 2 wheel high and 4 wheel high, neither sounded different than the other.

Now, I don't know if the whirring only happened after it warmed up or if it was going on all the time and I just didn't notice it.

Last thing: when I got back home the truck had no problem sitting in drive completely stopped.

So... anyone have any ideas? Thanks all, it's much appreciated!