Thanks for all the replies: excellent experienced based information.
Update: I couldn't see the top of the diff from under the vehicle
on my back in the driveway when I first just tried to tighten the nuts, so jacked up the vehicle yesterday, placed a jack stand under the right frame rail, then pulled the right front wheel and approached the front diff from there..
Once I got a closer look (and rechecked my own photos) it was apparent
that the gasket had pushed out along the top edge of the carrier flange.
I snapped off the gasket that had poked up, then cleaned up the area around the flange using some CRC electrical cleaner spray (doesn't seem to damage paint as much as Carb cleaner, no acetone?). Also removed the nut of the top right stud and cleaned the stud threads and around the base of stud well.
Then stuffed some Ultra Black FIPG (what I had on hand) into the seam where the gasket was missing (flange-axle housing) and then around the base of the stud, then replaced the lock washer and a flanged nut, torqued it down to 20 ft lbs and let it sit overnight for the FIPG cure.
Also tightened all the nuts again, this time with a torque wrench, to 20 ft lbs and maybe half of them moved a tiny bit (in hindsight maybe could have removed the nuts and applied Insensitive Blue thread locker to the studs, then retorqued, maybe bought me more time??).
Figuring this is a stop gap, might be able to delay the repair awhile before I have to do the whole front axle service (FAS) to pull the diff. Last time the FAS was done is unknown (one side may have been done about 5 years ago? by the PO) so had to do that anyways.
Here's some photos: Top photo is the piece of gasket that got pushed
out, note the partial hole far right for a top stud. Bottom photo shows the FIPG stuffed in the seam between the flange and housing and around the stud before tightening down the nut (moved the ABS line out of the way just for the photo).
View attachment 2152052
View attachment 2152053
I'll keep a close eye on it and post up more photos if (when) any leaks reoccur.
Also going to do the axle housing bypass mod once I can find more of the correct hose.