That's a very nice looking set! Really strange that there are no results on Google which means it must be pretty rare.
I can't tell you much more about the model but, as I am also interested in trains, I think it was made in 1958 or 1959. That's because the New York Central oval on the box car was introduced on the real railroad in 1958. This is a test version with the "CENTRAL" bar below the centerline. This was superceded in 1959 by the final version where the bar was moved up to the centerline and "SYSTEM" added below.
What I find very interesting is that the paint scheme of the locomotive is not at all from New York Central! Their locos were two-tone grey ("Lightning stripe" scheme) and later black with white stripe ("Cigar Band" scheme).
The model's livery was clearly inspired from Baltimore & Ohio's "Capitol" scheme, also the number 88 would fit a B&O F3 diesel (in the photo below #87 is shown). Even the NY logo on the front looks more like the Capitol logo than NYC's.
Why Mego chose to replicate this livery, change the colour to red and then letter it all as New York Central I don't really understand.

- BaltimoreOhio_F3AB_87.jpg (58.64 KiB) Viewed 7136 times