Sounds like the tech was out enjoying your truck to the point of trans damage............So I took my truck to a highly recommended shop in my area because my lights were flickering.I checked my connections, batteries and alternator were less than a year old so I thought a pro could figure it out fast. He did,bad batteries( crappy tire) but on a test drive he lost 2 gears in the transmission! I just bought a NADP Heavy Hauler this summer WTF! NAPC says I had a electrical problem first, it's an electronic trans.... I didn't drive long with the problem, trans light never showed up while I was driving, and I haven't drove at the hp I told NADP I was shooting for. NAPC is talking to the mechanic about it, I hope there gonna warrantee it, i did not wanna buy myself a trans for Christmas. So if in doubt don't b cheap buy 2 new quality batteries.