Thanks everybody for the help. Update. Although the fluid level is correct, I dumped another quart+ and has over 10 quarts in it now. No change to the issues. After it engages it will shift back and forth through all gears at idle. These trucks have a removal cover and I can clearly hear the pump when it is working. When accelerating normally, the 1-2 is firm (like a TF2 installed but, doesn't have one). The 2-3 flares every time and slips like it was thrown into neutral. Let off the gas and it moves to 3rd and operates normally while in 3rd. KD or quick acceleration causes the same thrown into neutral sound. Fishy, IDK the condition of the TC. If the TC was broken would it exhibit the stated symptoms, make noise, shake etc? Also, doesn't the 66 have a 19 spline TC?
