jaymartin17

trying to to see if I can get help from anyone. I have a 2013 Silverado 1500 with a new 6 speed transmission I just put in. The truck was in an accident where water damaged the transmission and went into the cabin. I have the truck up and running again. ( No damage to the engine just the previous transmission. ) However , the transmission works fine when shifting in P,R,N,D but when I start driving in D the RPMS just increase there’s no shift into the gears. The M mode (manual) also doesn’t work. Gears with number are not showing up like they used to. I was told by the transmission shop it could be an electrical issue as there is corrosion in the fuse box from the water and their scanner is not picking up any transmission codes. Anyone have any idea what the issue could be or could narrow down to a couple issues. Thanks in advance