I have an account of one being unloaded and it was apparently the overhead crane in the freight yard. They must have set the wheels on the track and lowered the engine onto them and then moved it to the shop for the rest of the work. Do not know why that work was not done at Burnham as the 490s were constructed there.
The mudhens, 470s, and 480s were all unloaded at Salida where there was a ramp for unloading off the flats. The tenders would have been on a separate flat, so they would have been moved to the shop to prepare them for service. The news accounts indicated that the first 480 arrived about two weeks before the first test run was made.