The 6G72 and 6G74 are notorious for leaking valve covers and eventually killing alternators, the valve cover gaskets will also usually fail in short order after replacement! Getting tired of this after replacing them 5 or 6 times with different brands and replacement mint condition valve covers, I set out to find what would work and found a cheap solution.

(1): Once you have the valve covers off, I recommend using a heat gun to warm up the valve cover gaskets to ease in their removal, if they have never been changed they will be hard as a rock when cold and almost impossible to remove. When you warm them up, they become pliable and you can use a pair of needle nose to peel off large strips at a time.

(2): Thoroughly clean the valve cover gasket seat(s) and the mating surface on the head(s) and insure no leftover oil is present, I would use a wire wheel to clean the grooves and remove as mush paint as you can. Test fit your gaskets into the groves so you know what orientation they are supposed to be ( I swear the first couple times I installed new gaskets I thought it was a puzzle lol)

NOTE: Perform step three on one valve cover at a time to insure accuracy.
(3): Use black or orange RTV and apply a generous bead along the gasket seat on the valve cover (where the gasket sits down into) and let it sit for 5 minutes. Once the timer is up, place the gasket into the groove and then run your finger along the gasket while applying consistent light/moderate pressure to insure the RTV is being squished into the gaps that are in the gasket seat (these gaps are leftover from the manufacturing process), wait about 10-15 minutes and carefully install the valve cover onto the head.
Bolts = 26.55 IN-LBS or 2 FT-LBS(Use blue Loctite)

NOTE: Please allow 24 hours for the RTV to cure before starting the engine.

Explanation:
The valve covers have two fatal flaws which causes the excessive oil leaks. First, the gasket seats have folds and gaps in them from the assembly method which mean consistent pressure is not supplied to the gasket and also means it won't sit flat in the groove. Secondly, each valve cover is a two piece unit which has been stamped together to make a single cover which in of itself wouldn't be an issue except that there is a large gap between each piece which allows oil to pool along the top of the gasket because of the aforementioned gaps and folds. Believe it or not, even Fel-Pros website mentions this could be an issue in some scenarios and RTV is the solution for it. You can read it here under section "When to use RTV".

If you have any questions, fire away and I'll do my best to answer them.