I pulled 3 sets of Valve Covers off of two 6.9 and one 7.3 this summer at PNP.
Of course we had he Alternator, Fuel filter bracket. Air cleaner etc... removed.
The VC bolt next to the AC box and i think one on the back side are the 2 most difficult to remove.
If the air box could be removed, it would be a straight shot to that one bolt.
I don`t know if the engine mount on the passenger side was losened up, maybe the engine could be raised enough to make it easier...? IDK
I had a leaky water pump a couple winters back, so had a shop replace it, too dang cold for my skinny a r s. Had them replace the VC gaskets, and leaky PS Pump.
Several months later the covers were getting wet. On the drivers side I pulled the bolts, blew out the holes with Carb cleaner, and then with an air hose with a rag over the holes to keep it from blowing back at me.
Also degresed the bolts.
Then used red or blue lock tite, don`t remember. After a year that side was clean, oil free of leaks.
The Pass side is a mess. Going to get to one of these days.
Goat