Age Identification II

[Banjopicker]

Thanks to all who responded, and I enjoyed the levity!  I have read all and am responding to a "suggested nugget" of info.
The set consists of:
the Santa Fe  EMD GP 40 Diesel, the Santa Fe caboose, a Georgia Pacific 51' pulpwood car, a Georgia Pacific 48' car with logs, a HD 51' box car, (Coronet Paper Products, a power pack, box of 36 pieces of signs and telegraph poles,, and a box of track.
Someone has written "Dec. 1987 on the original shipping box. 
Does this info help in the dating?
Thanks to all for any  and all feedback.