So I finally got myself a high roof Diesel T350 SRW extended. Its a 2015 with 100K miles, and was Florida kept (I live in WI). Anyways, I am super pumped as I finally found the build and properly priced vehicle. Everything was great until i dropped it off for a review from my local Ford dealership. I purchased it from a non Ford dealership, and I do sort of trust the diesel guys at my local place. I did purchase a 50K/3yr power train warranty.

Anyways: Driveshaft did have a dent in it which was causing a little rumble at about 55MPH. I saw it myself, and it wasn't that little. I didn't really notice it during the test drive, but I said go ahead and replace it. So that was $1800 with an oil change and inspection since they replaced the entire **** thing. Its 3 pcs no? Anyways...Stung a little, but I did have some $$ set aside for this case. Now I have driven the vehicle for about 300 miles, and the rumble is completely gone I am now familiar with a little bit of whining from the rear end and small chirp under hard accel from unloaded state. Not always there, almost have to try to make it happen. Other times it seems like I dont have to try at all. I guess understandable if that driveshaft was out of balance for God knows how long. Pinion bearing I am sure took some radial forces it was not intended for. But thats not all. In third gear, mid third gear accel range, there is a slight hesitation/drop in the engine RPM (about 200rpm) then it picks up and accelerates as usual. Its very very minor, but I do pick it up. Some other passengers dont even notice even when I point it out.

So here are my questions. I do have videos of both of these if you would like to see them.

1. I am bought into the fact the rear end may need either backlash adjustment, or maybe even a full replacement. (backlash is pretty noticeable from D to R shifting and watching the driveshaft). I would like some recommendations on what to do here before going full Monty on a full rear end job. Even some suggestions for where to get the new pinion and gear from. I have the 3.31. I could do the rear end myself if needed, but not familiar with aftermarket brands or quality for this unit. I would love some warranty coverage, but I am skeptical what the dealership will say. Or if it will be too late before they commit.
2. Is this trans shift issue just some programming and normal for these vans? Maybe not an issue at all, I dont have the experience with these to know. I would like to address this sooner than later if it is actually an issue. Its also not constant to a single RPM range. l can observe it happening on light throttle at lower RPM, and also when hard on the gas the same things happens at higher RPM, so it seems its mid 3rd gear related. Not loss of power (engine) at certain RPM related.

I am about to build out the interior, but before I do, I need this thing rock solid performance wise or I just wasting time and money. Any help is appreciated. Feeling a little wrung out on this purchase so far. Hoping for the best.