Help! My truck squeals!
 

Ok I have the 2.9, I'm posting here because in the 3.0 page someone said here was better because both the 4.0 and 2.9 are in the same family? Pushrods? Idk. Anyways, I just bought an 86 ranger 4x4, and after I drove about 40 miles, and hit stop and go traffic, it started squealing. At first it sounded like a brake pad was stuck to the rotor. So I pulled over and took both front tires off, because I couldn't tell which side it was coming from. When I realized it was not a stuck pad, or low pad, I thought perhaps the bearings were beginning to over heat. So I took them both apart and regreased them. When I test drove it, it seemed to stop the problem. So I continued on my way, but when I stopped 40 miles later to fill up, again, the dreaded squeal. After talking to my dad, a mechanic of 30 years, we came to the these conclusions:
1. Perhaps the torque converter?
2. Perhaps the wrong fluid?
Please if you have any idea, Help!