You hit the nail on the head, Mike...
Parts are parts. I remember the games we played on the class 1...
We had to show that we could produce power as a roundhouse supporting the railroad, but we had to wait something like 6 weeks for a one off weirdo airbrake part for one our SD75's.
268 broke it; we stole the part from 273 for 268; then from 293 for 273, then 264 for 293, then 254 for 293, then 253 for 254.... then finally we got the new part. We got to show that we sent ~7-8 locomotives out for only needing one part replaced...
Of course, things were slightly different in the steam era, but - in most cases, parts are parts.
Mark Huber
Hyce on YouTube