Those GP18s look lovely. The day I eventually get around to backdating the Kalamazoo route to the 1980s, I should think the GT power would be right at home.
Might it be possible to do one as Tennessee, Alabama & Georgia Railway No. 50; "The Dave E. Hedges"? I should have some of the TA&G art-work if needed. The unit became a Southern Railway loco (SOU 179) in 1971.
https://hawkinsrails.net/shortlines/tag/tag50a.jpgLooking mighty fine, as ever.
'PullmanCar'