A Budd car is one engine that I do not yet have on my layout.
I am waiting for a PS2 or PS3 version of CP or CN to be realeased by MTH. I once had an opportunity to purchase a 4 car CP set, an MTH PS1 (it looked awesome). I was concerned with the cost and practicality of converting it to PS2, so I did not purchase. I have not seen anything close since.
Still looking and waiting for MTH to release a CN or CP Budd RDC in PS3