Helll everyone. I have a problem and hope I can find some help.

Little back story. The reverse went out on me while I was on a trip about 1000 miles from home. All other gears worked fine. Drove it home and rebuilt transmission. Reverse still didn’t work but all other gears were fine. Changed the reverse piston, reverse works again but now O/D is not working. Decided to change all pistons because the 2-3 accumulatior was blown and we thought that was the problem.

So, i can drive the truck in 1st and 2nd gear but once it hits 3rd, the rmps go up to about 3000 and it drops into neutral. I turn my o/d off and dive like that but now my o/d light is blinking. O/D was working fine before we rebuilt that transmission. Could it be a sensor that’s out? I haven’t brought it to get the codes read because I don’t know if I can drive it that far with that light blinking. Any help would be appreciated!! Thank you!