99 Explorer v6 4.0 transmission questions because I don't know what I'm doing.

[Block Maker]

So my problem is I bought an explorer great price great vehicle problem is my transmission is going out. Mainly reverse and drive won't work. Unless the fluid gets warm to hot.I have a 99 MOUNTAINEER that I can part out. My confusion is this. Can these two swap tranny's? If no can any parts from the 4R70W be used in the 5R55E. And if that's not going to hello when I chose to buy one how do I know it will be the right one I can't find any thing on line that helps me decipher how to choose the right transmission. And hello is more than appreciated. Thank you

 

[BrooklynBay]

Welcome to this forum! Parts between both transmissions won't interchange. Are there any transmission trouble codes? Did you check the fluid level? When was the last time you replaced the fluid & filter? Did you check the valve body gaskets, and the torque of the valve body bolts? Did you check the main pressure, and the EPC pressure with a 0 - 300 PSI test gauge in each gear setting? Did you adjust both bands?

 

[Block Maker]

First let me say thank you for replying and glad to be apart of this forum. I'm currently in the process of having all those things you mentioned done. I will be sure to leave the results as soon as I know more. Thank you again for your help.