Swaping out the rear end of my 8Kw was pretty easy for me.
2 A/C wires, the starter and wires came off, about 8 bolts and the housing was off. Then the rotor, 6 bolts and it was off.
Reverse and done. Not even a full days work unless the bolts are rusted in. And mine was a mess.
For a yard to swap rear ends, if tbey charge more than $1000, they ran into something unusual.