|T. S. Martorano Collection|
This is an early bolster with a notably sloped face in the bolster end. This is the truck included in the Red Caboose HO scale X29 model.
This and the following image illustrate the "box" bolster. This truck was offered by Sunshine Models as a set of white metal castings to be assembled by the modeler.
This bolster is what I have dubbed the "ARA" bolster. I am not aware of an HO scale offering for this. Should Kadee get around to offering an 'HGC' version of their 2D-F8 truck, I would lobby for this as it could be used as a Type Y stand-in, most notably for several PFE reefers. That beer can-like thing where the outer right hand spring is supposed to be located is a Miner snubber, which was supposed to reduce harmonic oscillation and improve ride qualities. There were other flavors. See the CP chapter in your 1932 ARA box car book.
This is the last and most "modern" of the bolsters with a vertical web cast in the center of the outer portion. This truck has been reproduced in HO scale by Bowser.
Note that while I have highlighted these as shown on X29s, they were used on many, many others classes of 50 and 55-ton PRR cars, so having representations of all of them in HO scale is a good thing, even for non SPFs*.
*Slobbering Pennsy Freaks