These N Scale PRR Class 2D-F12 Coil-Elliptical freight trucks were found under many, many PRR typical freight cars such as classes FM, F32, GLa, GS, K7a, XL, X23, X25, X25a, X28a, X29, X31, X31a, X31b, X31c, X31f, X32, X32a, X32b, X32c, X33, X33a, and X36 (per online sources).
Designed for Fine N Scale kits, they should also work with Red Caboose and other PRR cars from various manufacturers.
These trucks are designed for the 0.540" x 33' wheelsets of your choice. Some light cleaning in the axle point pockets with a Dremel 105 engraving bit after print cleaning may be required for smooth rolling characteristics. A Micro-Trains bolster pin will fit the bolster hole in the truck for mounting under your model.
An 8 pack of trucks can be purchased
here.