A non-6.0 is a lot easierest to put Vette servo pistons in. I'd rather regear front diffs than rear 'cause I've done more and it pays better. Rears aren't that bad either. I'd probably charge $450 on the side for a double gear swap with someone I did not know. That's half of your quote. Leave the 73's unless the gearset is the source of the noise. If not, swapping some bearings is cheaper than others. You need more information.