The Lionel #497 Coal Loader:
According to the following link, Raymond Loewy designed the #497 Lionel Coal Loader. (You will have to scroll to the 1950's era in the link below to see the very brief notation.)
The Pennsylvania GG-1
Also as properly noted by subsequent posters in the thread regarding "Most Beautiful Electric", it appears that Loewy did not actually design the Pennsylvania GG-1, but, in the opinion of many observers, improved its appearance with his additional design input. (I will correct the OP in that thread to be more precise.)
Here's the passage from WIKI:
"Later, at the Pennsylvania Railroad's request, he restyled Baldwin's diesels with a distinctive "sharknose" reminiscent of the T1. While he did not design the famous GG1 electric locomotive, he improved its appearance with welded rather than riveted construction, and he added a pinstripe paint scheme to highlight its smooth contours."