New Clutch, slipping sometimes in high gears

Hi all,
First time posting so please go easy on me if this is the wrong forum or if I break any rules, ill try to be good.

So I have a 2010 freightliner cascadia with a 2015 Detroit dd15. 468,000 miles on it. I just purchased this truck 3.5 months ago at 430,000 miles. This was the same truck I drove as a company guy for 6months prior, and I know they recently replaced the transmission and the clutch.

37,000 miles after purchasing the truck. My clutch gave out. As in I put the truck into gear, released the clutch pedal, and nothing happened, rev engine, nothing happens, try multiple gears, nothing happened. Get a bad diagnosis that the brake line froze near the brake chamber, melt it down for 5 hours. It works again, i chalk it up to cold weather (25 degrees) (yes I now realize I probably should have known that it was not a frozen brake line since the truck did not even try to move). I drive about 1500 miles and it goes out again, same problem, this time with no luck, although also in cold weather (the first time it was below 25 degrees again that week).

This time they opened up the truck and suggested a new clutch. They showed me the old one, and I guess it does look old, worn out, and the bell housing was filthy. So I had it replaced.

The fork was worn down (also was 38,000 miles old)
So I replaced the fork, and got a new clutch assembly to match the new clutch. I also had the rear main seal replaced just to be safe.
I Also had the flywheel resurfaced.

Now i noticed a couple things.
When I am driving, there is a "dripping" or "leaking"sound... it only occurs when the truck is rolling, i have no idea what this is or what it could be, does anybody have a guess?

Also the clutch is slipping in high gear. Sometimes it will catch itself, but usually I release the gas to match rpms and it catches on.

I am.told there is a breaking in period. However I cant find much online about that and I am skeptical. What do you guys think?

 

Thanks for the input! The mechanic is a long ways from home but hes offered to take a look free of charge, i just need to get it out there.

It is a hydraulic clutch, my understanding is that they cant be manually adjusted, they are self adjusting. We replaced the rear main seal so i doubt that its leaking.

That leaves a bad clutch, or something else. I will definitely keep you posted.

 

I think the frozen brake line assesment can be chalked up to bad, newbie TA mechanics, and a newbie owner operator (me) who doesnt want to even think he has clutch problems, and also a little bit that i knew they clutch and tranny were new.