The Lionel Mark Twain Zephyr is the Pioneer Zephyr with different car names.
The Lionel model:
Notice the dip in the brow of the model. This was unique to only the Pioneer Zephyr.
The original PZ consisted of a Power Car/RPO/Baggage, Baggage/Coach, Observation/Coach/Parlor.
The MTZ consisted of a Power Car/RPO, Baggage, Dinette/Coach, Observation/Coach.
The Lionel model is at best a stand-in for the Mark Twain Zephyr
The Prototype:
Plus, the Lionel model lacks the full baggage car Becky Thacher.
Rusty