Just bought a 1997 Ranger XLT Super cab 4.0L 4x4

Zero tranny problems from a stand still or at low speeds. However a couple of times at moderate speeds the tranny is just not getting into a gear. I hit the gas pedal and I just hear the engine revving pretty good. I take my foot off the gas, slow down a little more and same thing, it revs up, almost like it is in 2nd gear when it should be in 4th or the overdrive gear. But again, never any issues getting up to speed.

One last thing, someone played with the speedometer. Carfax history shows a few registrations and recorded mileage has been as high as 181k whenthe car wsa first registered in Florida on 9/18/2013. Carfax record then shows on 9/19/2013 EXEMPT which is because cars over 10 years old aren't required to report mileage. I should also add that the car was registered in PA in 6/28/2012 with recorded mileage of 166449. The guy I bought it from said it had 151k and that is what the odometer said. He told me that the odometer was acting really shaky or not working at all and he thought it was a speed sensor. It was only after he told me that and I ran a car fax that i noticed either he or someone recently must have played around with it. After talking to him, he told me he bought the car in late october and I ran a different car history report and it came up with another registration date of 11/4/2013 which matches up with the insurance paperwork he has in the car. So ultimately, whoever sold him the car bamboozled him. Presently, the tachometer works fine but the speedo and odo aren't doing a thing. Is there any possibility that there is some sort of speed sensor that would cause this to shifting issue to happen at speeds of appx 45-60 mph?

BTW, I went to get the oil changed today and they said what little tranny fluid was there looked terrible. I had them go ahead and put fresh tranny fluid. The problem isn't a constant one but it happened a couple times before and after the fluid change.

Well I took the truck over to AAMCO today to have them take a look at it and give me a diagnostic. it threw a couple of codes out at me

P0500 Vehicle Speed Sensor
P0756 Shift Solenoid B

The guy there said that the sensor that is in there looks like it is new so he's not sure why the speedo isn't working. Said it could be a problem with the cluster and I could try changing that out. As for shift solenoid B, he says that is an internal part of the Tranny and with the age of the truck, probaby gonna need to drop the tranny to get at it and fix it to the tune of $1500. $500 for parts and $1000 for labor. That doesn't sound too bad to me but I've been out of the car game for awhile so I really don't know what things cost these days. Seems like even if I just got an entire junkyard tranny that its pretty serious labor involved and I'm better off just having my tranny rebuilt. Opinions anyone?

FYI, I found a ton of info on this shift flare issue on the explorer site. It appears the valve body needs replacing.