With no previous transmission problems, I was on a recent trip and I noticed the rpm on my tach was running about 2500 rpm at 60mph in overdrive (normally runs in the 1700-1800 rpm range at this speed). I manually downshifted to 3rd gear then back to overdrive but rpm remained at 2500. I continued at this pace for about 6 miles to a local Wal-Mart so I could check the transmission fluid and in case I needed to purchase some Dexron. Coming to a stop at my exit, I noticed the transmission did not drop down to 1st gear. When I accelerated, it was still in 2nd gear and slow to move. The passing (kickdown) gear was not operational either. At Wal-Mart, the fluid level was fine and had a nice pink color with no burned smell so I made no additions. Upon leaving Wal-Mart, I shifted manually to 1st gear to see if was working and it was. I then manually shifted up to OD (at highway speed) but the transmission would only go to 3rd gear. On the drive home, I left it in OD to see if there were any changes. No changes at all. So I have a 4L60E in a 1995 Chevrolet K2500 P/U(6-lug) with 95,000 on the clock. Overdrive is not working at all, 3rd and 2nd gears are fine, 1st gear works fine only if shifted manually from a stop. Please HELP!