can anyone estimate the labor time to replace all bearings, ring and pinion, rear brakes and all spring hardware axle bearings, pinion race on a 2007 f150 with 373 rear

 

Depends on how much experience you have, lets say not much experience and first time doing this about 5 hours if you are replacing the pinion bearing/races, maybe only 3 hours if not replacing the pinion bearings/races.

 

I was just quoted 10 hours to remove and rebuild the rear diff carrier/ ring and pinion

 

10 hours is a **** ton of time, I pulled a transmission out a 2014 explorer, cracked the case and fixed the issue, reassembled the trans and reinstalled it for I think around 12 hours.
I am wondering what exactly you are getting replaced that is not inside the rear end?
What size ring gear do you have? I believe you can get the 3.73 ratio in more then one size rear end. The three sizes are 8.8, 9.75, 10.25 inches.
Here is a exploded picture of the rear end internals, can you circle what parts you are having replaced?