MP54 Questions. Oddball trucks??

[ApproachMedium]

Question for the PRR people out there. I am a huge MU commuter nut and I bought a set of photographs last year a train show of them. I was just going thru them and realized that the one photo where you can see the trucks, they are very very different than the standard MP54 trucks. The car number is 647. Photos are attached. Its not the only car that had these as you can see in the second photo. The first photo is a photo that I own, photo credit to Gene Collora who took the original.

[ExCon90]

I thought we'd have heard from some experts by now, but I looked through William D. Middleton's The Pennsylvania Railroad Under Wire, published by Classic Trains, and beginning in 1950 the PRR equipped 99 MP54's with equalized trucks, roller bearings, and aluminum-sash windows (and I think more powerful traction motors). That top photo shows roller bearings and aluminum-sash windows, so I would guess that's one of them (I think they were classified MP54-E6). They rode beautifully and had spiffed-up interiors including recessed ceiling lights, very much in the style of streamlined coaches of the '40's and '50's.

[ApproachMedium]

Interesting thanks for the info. I t looks like its actually got some of that info int he wikipedia page too. I shouda looked there first.