Hi I'm new to this site as well as diesels. I've never owned a diesel but have used them at work for a few years. I know what to look for when it comes to basics, but am not 100% sure with the truck I am buying.

There are a few small problems possibly and I want to know what someone with more knowledge on these trucks has to say...

When the truck started up, there was a tiny puff of white smoke, but went away immediately, is that common on startup or should I check compression, rings, injectors?

There's also a slight rattle when I let off of the gas in first or reverse. it almost sounds like a grind but i don't think so. It's a 5spd.

The transmission had a few small drips from where a piece of sheet metal is bolted on? Not sure where this is on the transmission but I've seen this on lots of these trucks but know nothing about it.

There seems to be a slight vibration at higher speeds (65-70+). I'm not sure if it's a driveshaft axle or if it just needs an alignment? A 2001 f250 felt identical when driving it so it didnt seem out of the norm but just concerning.

Lastly, I still have to check the turbo spline, but the previous owner must have cut a hole in the airbox for better flow. If this bad if there is exposed air filter? I read that the if plastic clips are used insted of metal clips it could be a problem, but is the box itself a concern?

Any other comments or concerns with a 165xxx mile diesel that I should look for?

Thanks! Any help is super appreciated and hopefully I can be a real member here soon enough!