First, I had the tranny replaced at 85K, my '01 Durango now has 118K. The durango started hesitating on left hand turns, it would seem like it would bog down or even rev a little until I came out of the turn. I checked the fluid level and it was a little low. I topped it off. A friend said to use some Lucas Tranny Fluid additive. I did and it was just marginally better. A week or so ago I was going about 40mph and I heard a crakling noise that sounded like it was coming from the tranny. I slowed down and put it in neutral and it stopped. I got back up to speed and it did it again. I pulled in the drive way (on a slope), put in it park and it rolled back. I again checked the fluid and it was down a bit (did not notice any on the driveway at any time) Again I topped it off. When i went to pull out of the drive I put it in reverse and rolled back down the drive, once I hit the road I pressed the gas to back further up and the engine just reved and then reverse came in slowly. I dropped the pan tonoght and changed the fluid and the filter. Fluid in the pan was dark but the fluid on the top side of the filter was not as discolored. I take it the filter was clogged. Put in the ATF-4 and drove it this evening. No crackling, however reverse is still slow to engage. When I put in it park it rolled twice and locked into parking gear 3 times as it should. Before I take it to the local shop, any ideas on what I am looking at?