TL;DR: My dealer service department screwed up and put the wrong gear ratio in my truck's rear-end. I noticed the truck shuddering and behaving "weird" in 4WD. Engaged it maybe 4 times since the screw-up, always in slippery conditions. It still seems to drive fine in 2WD. What should I all be looking at for damage?
Truck: 2009 Ram 1500 Quad Sport, 5.7L Hemi, 20" wheels - everything is stock, no mods - where would the weak link be in the drive train that may have broken?
Full Story: In 2014 there was a recall on a pinion nut in the rear end. It affected my truck, and as part of the recall, they replaced the gears and bearings in the rear diff.
My truck was built with 3.92 gear ratio. For some reason the recall kit provided 3.55 ratio replacement gears. I almost never need 4WD where I live, so this did not show itself right away.
Pulling my boat out of the lake last summer, I needed 4WD on slippery concrete. Felt some shuddering up the ramp, but just assumed my dang trailer brakes were locked again. At the top of the ramp, went to 2WD, fiddled with the trailer, carried on, didn't think of it again.
This winter we had abnormal snowfall, so I needed 4WD a few times. It worked a treat in the snow, but when I got onto the wet asphalt (i.e. not as slippery), the truck started shuddering and felt like it was binding or pushing against something. Went to 2WD and carried on, but that's when I booked my service appointment.
Now the service department calls to report their findings and they say its "the strangest thing ... seems your truck was built with 3.92, but somehow we put 3.55 in the rear end during that recall ... discrepancy between build sheet and spec sheet (or something)".
Anyway, what I'm worried about is a "bare minimum" fix, and I want to know what they should all be checking and/or replacing as part of fixing their screw-up.
Thanks for your time