Tim,
Yeah, I don't think the Shawmut did much of anything except paint over "Monon" and the engine number and replace it with their logo. They bought all the J-4's but the 576 and 578, which went to the TA&G. Anyone have any photos of the two engines that went to TA&G? It appears they were both scrapped by 1951, so they didn't have them long. I don't think I've ever seen a single photo of them.
I am a bit surprised the Shawmut didn't add a "doghouse" to the top of the tank like their other locomotives. The Tennesee RR didn't waste any time adding them to the 2-10-2's they bought from the Monon. More true mountainous terrain down there vs. Western PA, maybe.
Eric