I have a 2006 1500 QC 4X4, last week I changed the trans fluid and filter and somehow managed to over fill the trans by about 1.5 Qt. I warmed it up and checked the fluid level, draining out the excess. I backed the truck out of the driveway and went for a drive, when I returned home reverse did not work at all. THe back up lights work but the trans feels like it is in neutral. I had it taken to the local stealership ($200/hr rate) and they road tested it and confirmed that all is well in drive all forward gears work and it shifts fine but reverse doesn't work. They also dropped the pan and checked the clutches? When they checked there were no codes stored.

Is there anything I should check or do, the transmission had zero problems before. Also the two shops I have talked to estimate $3000-4500 to rebuild this trans. I can buy a Sharadon stage II and an Edge convertor for $3000, is there any issues (computer?) to bolting in a new transmission?

Thanks