Denali Front Differential
 

I believe my front differential is on the way out, due to lots of metal shaving when I changed the fluid, also the drivers side is leaking and the roaring noise that I hear under acceleration and deceleration. There is no play in wheels at 6 and 12. Small amounts of play at 9 and 3 but appears to be inner tie rod or pittman/idler arm.

I was searching and found rebuilt differentials at GMGearheads - Home. they have the stock rebuilt for $875 and a Pro-line series that has modified side-bearing locks and 3yr warranty for $1450.

Is it worth the extras cost to get the side-bearing locks?

The main failure on that model drive axle was the right side diff bearing spalling and screwing up everything else, depending on how far it was driven. I would probably spring for the upgraded locks and warranty since the old factory design lock has to be bent around just right to work. GM redesigned the carrier to fit the newest style adjuster lock into the older style axle carrier but I did see those locks spin too; albeit rare and usually because the vent tube end was hanging in the left wheel well, shoving water into the axle.

There you go, make your own choice.

I had the dealership here in town rebuild mine, $1100 out the door with a new ring and pinion.