Here's our MPC set - An early 70's Silver Star set that I inherited from a relative, back in the early 80's.
No original box (a brown paper grocery bag if I recall correctly).
We did some cleanup and had the SoS board repaired (which now needs to be repaired again) and we added fuel trailer, coal load, containers, etc.
Yes, the cars are def. starter set quality but they've held up well and the set still runs great.
