Book hours on W126 rear-differential swap?
 

Can someone look up the book hours listed for doing a rear differential swap out on a 1988 300 SEL?

My buddy needs his replaced and they are telling him 5-6 hours labor, which seems excessive compared to some of the DIY stuff in the driveway with a jack I've read about on here. It seems like a modern shop should be able to blow through that kind of job in hardly any time with all the fancy tools.

Any ideas on where to source a good used one?

Rear Differential
 

1984 300d Turbo 137k
Its 5 Hours By Alldatadiy.com For 300d 1984 Very Good Yearly Rate
Information Guide.