Clinchfield (CCO) Railroad Diesel Livery Dates

I found nothing on line re: the subject. From my TS2020 simulation [re: The Clinchfield Route/Elkhorn City to St. Paul ], I know that Clinchfield used only two (2) paint schemes on diesels: 1) Gray & Yellow-first and 2) Black and Yellow-last. Does anyone know what year the RR transitioned from #1 to #2 paint schemes?

Wow! 199 views and no one knows the answer. any body know a reference book or site I can view to find out? Thanx

Lots of people can’t make any sense of the thread without opening it to read the actual question … only to find they haven’t a clue about the answer.

Mike MacDonald (former poster ‘wanswheel’) might be able to source the information, but Kalmbach moderation cut him off.

In any event there won’t be a hard date. There may be a hard date for when the first of the new scheme appeared, but there will be period of years where both schemes will be operating side by side.

I do recall a gray CRR F7B at Monon’s South Hammond yard in the early 1970’s. Presumably it was en route to EMD as a trade-in.

A hard (or even estimated) date for when the first of the new scheme appeared would answer the question I have. Also, I am particularly interested in which scheme came first: A) Black & Yellow or B) Gray and Yellow? I made an assumption in my first post but I have no idea which color scheme was “first”. Thanks.

Thank you very much!

The first black locomotive saw was in 1971.
The U36C’s were the first in this scheme.

Thank you.