4x4 rear axle in a rwd Tahoe?

[Marky Dissod]

This car is not my daily driver but more of a weekend and vacation cruiser so 3.73 should be about right.

No, 4.10 will be better. 3.73 is BARELY adequate at best.

I am also running slightly smaller diameter tires, so it will be about equivalent to a 3.80 with the stock size tire.

3.80 ain't 4.10. You've CLEALRY never driven a GM suv with a 6.0L, or a GM suv with 4.10.
Their 4L60Es last longer, and they get decent MpGs unless driven by leadfooted idjits.

It sounds like the GMT900 are a little wider so I probably don't want to mess with that.

0.5" wider on either side is not worth any concern. Open your options, don't close them.

... thanks Marky for the edit!

No thanks needed. For your sake, I hope you find 4.10 ...