Both of those codes are electrical related and saying that the ECU isn't getting signal from the speed sensor or lock-up solenoid MV 3. I would check for blown fuses or cut wires first.

Are you sure P0772 wasn't P0722? Here are the Trouble codes from the RAVE and im not seeing 0772.
Transmission Trouble Codes.pdf

1) you should check all the fuses. There are at least 2 fuses that are used for the trans ECU, I think it's fuse #12 under the hood and #24 inside.

2) Check the Auto Trans ECU and make sure everything is plugged in. The ECU may be your problem. You can buy a used one for cheap to rule the ECU out as your problem. Here is where it is.
Automatic Transmission ECU.pdf

3) Crawl under the truck and look closely at the wire harness near the trans for damage.

If everything checks out with the 3 steps above I would move on to checking the lock-up solenoid MV 3, the speed sensor. Also, you might want to check the ECU connector to make sure the pins that supposed to get power are getting power.

----EAT ECU connector pins.pdf
----lock-up solenoid MV 3.pdf
----This shows the speed sensor in step 6.pdf

Your codes don't point to this, but your symptoms sound like a possible bad XYZ switch. You can take it off and check it for damage, or just buy a used one for cheap to rule it out as the problem before going into the transmission for the solenoid and speed sensor.

 

Yes it is P0722. I checked the fuses and they are fine. Will unplug connectors and spray clean with electric cleaner and replug. Also while I'm down there I'll check for damage.

 

Okay since it's 0722 and not 0772 it makes things a little different. P0722 is torque converter slipping.

Are you sure you have enough Transmission fluid in there? Did you let the truck sit over night to cool, then check and fill the fluid with the engine running?

 

No I'm gonna do that now. I moved it to level ground yesterday and it's been sitting overnight. So start it up first then remove the fill plug to check level? Not gonna jack it up obviously since that would mess the level.

 

Here are the instructions directly from the RAVE:
Transmission Fill instructions.pdf

Yes. It's better with a helper.
block the wheels, pull the parking brake, and put the foot on the brake. Start the truck, have them go through all the gears (P,R,N,D,3,2,1) stopping at each gear for a second and then return to P. Leave the truck running and remove the fill plug. If no fluid comes out then add more until it does. Put the fill plug back in before you turn off the truck

(It might be smart to have extra transmission fluid and a pump on standby so that if you find you are low you can add it right then and there.)

 

Any recommendation on the ATF I should go buy to top it off with it? I have some walmart brand Dexron II and III rated fluid non synthetic at home.

 

From the RAVE:
Automatic Gearbox: Use Texamatic 9226, ATF Dexron 11D or Dexron 111 for refill and topping-up

Use the Dexron III.

 

This is what I use.
Get the Valvoline MaxLife Dexron / Mercon Automatic Transmission Fluid at Walmart.com. Save money. Live better.

 

What I meant was it's rated for both. I'll go pick up a transfer pump and then do this. You're right as well do it all at once.

 

You can at check to see if it will need more fluid before you go buy anything if you want. It might have plenty of fluid and not be your problem. At least save your receipt and don't open anything until you are sure you need it.