I found these numbers, and a link to the pages, about these little "pups".
SW600 Order Numbers
Order # Date Serial Numbers Model Road Numbers Qty. Weight Remarks
4449 01.62 26932 SW600 AZ Public Service 1 1 . .
4423 09.58 24745 SW600 Clinchfield Coal 100 1 . .
4267 03.54 19513, 19514 SW600 CNW 1280, 1281 2 . .
4269 07.54 19525 SW600 DEEX 213 1 . .
? 09.55 20665 SW600 GOCX 9 1 . .
4434 06.60 25682 SW600 Marathon Southern 1 1 . .
4252 06.54 19300, 19301 SW600 McLouth Steel 8, 9 2 . .
4262 02.54 19492 SW600 Northern IN Public Service 4 1 . .
? 03.55 20376 SW600 OH Midland Light & Power 512 1 . .
? 05.58 24679 SW600 Philadelphia Electric 30 1 . .
4450 09.62 27278 SW600 Public Service of CO 15-1 1 . .
? 04.55 20616 SW600 SOCX 9 1 . .
4275 06.54 19607 SW600 Texaco 23 1 . .
Updated 11.02.2003
http://yardlimit.railfan.net/emd/sw600/index.html