Hi all. I am new to this site and hoping to get some ideas on how to get this truck fixed. It is a 1999 GMC Jimmy 4X4 with 150K miles and the 4 button 4X4 selector switch. First problem-transmission: When driving very long on the freeway (more than 10 miles) truck shifts out of overdrive and will not go back in. Also, when this problem occurs, when you let off the gas the torque converter completely disengages. It shiftas really hard from 1st to 2nd intermittenly. It will run perfect for a while then starts shifting hard. Temperature doesn't seen to make a difference. Second problem-4X4: Cannot get the front diffefential to engage. It will shift into 4 hi and 4 low but the front differential will not lock in. Third problem-ABS: There is a clicking sound coming from the kick panel on the passenger side. Sounds just like the hazards are on but I beleive it has to do with the ABS because when you step on the brake pedal, even a little bit, the noise stops. Please help as this thing is driving me crazy!!!