Buses have a full width cargo box under the frame. Your part goes in that same space as Grandma's hatbox. So, any sharp corners/edges must be protected. And, anything that may rub off on peoples luggage must be protected. I use cardboard & duct tape on corners & edges & then use pallet wrap overall the whole part. Pallet wrap is like a 36" wide industrial saran wrap. If I am in doubt on wrapping or price, I wrap it to what I think is OK, then take it to my local bus depot & show it to the station agent (boss). Costs me about a 20 mi. drive ea. way but I am sure it'll ship & have a good price idea. If I'm gonna auction it, I get prices to three cities of various distances & use that to guesstimate a final shipping price. They have a website but in the end its your local agent you have to work with. I have a great one, done a fair share of shipping thru the yrs. with him. You must have the recipients phone # when its sent, they call him for pick-up at the station on his end.
Doug