Something to consider.... the TSB quotes a "warranty" time... this is the time that Ford pays to perform an operation in a warranty situation.
Just to add some insight to the situation (I'm not familiar with R&R of this front diff), I'll mention an operation that is near and dear to my heart.
6.0 diesel head gaskets pay 14.4 hours under warranty. Having done a few of these, I am proud to announce that I have honed my skills to the point where I can perform this operation in a little under 24 hours. That leaves me being unpaid for nearly 10 hours of my efforts.
Ford warranty times serve Fords purpose and may have little to do with reality. As a tech, I know what I need from jobs I am familiar with... under warranty, I have no choice.... in a retail situation I will set a price that allows me to ensure that I wont be rushed into leaving other concerns behind. If anyone feels that the Ford time is fair, I can only suggest that they perform the task....
I can only suggest that the original poster resort to other avenues for labour estimates. I live a comfortable lifestyle.. apparently, I can only keep some happy if I were to live in abject poverty...