Vibration at higher speeds...

After a couple of hundred miles I noticed that my truck was vibrating at higher speeds. This totally pissed me off. Already I'd dumped nearly $7000 into it (initial purchase, new motor + misc water pump, etc., shifter seat/bushing/boot, oil, more oil, drain plugs, insurance, registration...). I did tons of research before determining I had a driveline issue. I figured it was probably my rear driveshaft out of balance or something of that nature. But since I had zero idea how to figure this out, regardless of how much I read, I opted to take it to my shop.

Turns out the rear driveshaft was out of balance or something. They sent the driveshaft off to a shop to have it rebalanced and had it back to me in less than 2 days! After that, it ran pretty smooth for a while...

A few months later I had some new vibes at any speed over 30mph. I went back to the shop and one of the mechanics (Eric) came out to check it out for me (for free). He showed me that there was some slop in my pinion flange. I have to admit, I wondered whether or not this was the original problem but then remembered that disgusting tar-like oil that was in the rear diff before (and the hundreds of thousands of miles that had been on the truck before I bought it). So I drove it home and decided to do some more research.

My truck sat parked for a while and I gathered some other parts I wanted to replace. I haven't driven the truck since, but in the meantime I've done some other work...