You're not going to get a lot of answers because most just use OEM or a replica of it, so I'll help the best I can. I have a 2002 denali and I went through this same process about 6 months ago.
You've already found out theres no way a mag-hytec would fit. After I realized the Mag was a no-go, I looked at G2 covers, called them and was told there was no way any of them would fit it fit.
Although a few months later (After I was already done with my diff cover) I found this on an avalanche forum:
Its a G2 Torque diff cover with a qa1 panhard bar and clearance
After that I looked towards the PML cover which was heavily documented that it would fit our rigs but I couldn't justify spending that much money for it and I didn't like the way it looks.
I finally ended up at the TA performance girdle. The cover provides extra fluid capacity, actually has a drain plug (what a concept right?), has two load bolts that reinforces the bearing caps, and its hands down a work of art IMO. My research led me to the third gen forum and it received a lot praise claiming it helped their rear end live longer. As a third gen owner knowing how weak the rear ends are, that review was all I needed.
I bought the low profile one (TA_1807A) and was told it fits no problem...Well it didn't. I had to grind one of the fins a little bit and notch the panhard bar a little bit. No major surgery but to weekend warrior who wants a bolt-on affair this may not be ideal. Maybe I was the one unlucky one whose didnt fit, maybe I was sent the og depth one, maybe they don't know their asses from...anyway, who knows. I am slightly concerned when I go low if it will clear a tubular panhard bar, but thats another day.
Sorry about the book, heres the cliff notes version:
- Expensive PML is the only 100% documented aftermarket diff cover to work with our rigs.
- I bought TA performance girdle, very minimal modification to panhard bar and girdle fin and it fits. Maybe QA1 wheel clear it?
- worth it? my diff stopped howling and I smile every time I'm walking to my truck.