In What I have seen, it seems to be a specific job by job question. There are few contractors out there that know how to rebuild 100 year old railroad specific parts! Plus sometimes your paying the contractor for their specific learning curve on the project. I am currently working on a project that will outsource some body work and painting for a Santa Fe locomotive. In this case, the volunteers and museum personal know that a much higher quality job will be obtained. The VALUE of the outsourcing will be huge, and well worth it.