4r100 slippage.
 

I have a 99 F350, 7.3, 4r100, 4x4. 257k miles. Daily driver, ocassional towing. While driving in town empty it began slipping at takeoff, 2,3 and 4 gears still good. Rapidly worsened to no forward motion from a stop if in drive. If I put it first manually it goes. Reverse works. No OBD codes. Pulled pan, spotless, zero debris, fluid clean and sweet. Any ideas of what to look at short of complete replacement. Thanks.

I would do a complete rebuild with a good converter

I wish I could afford that, but times are tough.

Sorry friend but it sounds like your trans is toast.