These work great for U.P. "Q" trucks used on Non-Standard, CA, and CA-1 wooden Union Pacific cabooses. (Micro Trains makes the CA, I kitbash my CA-1's). They also are great for using under U.P. CA-3 and CA-4 steel cabooses by Intermountain (you have to move some of the brake details and fill and re-drill the truck mounting holes). Journals, springs, brake details are identical to the U.P. "Q" trucks. The only difference I can see is the top oak beams have different "bolthead" details and are perhaps not quite as "tall". However, prototype photos of U.P.'s "non-standard" cabooses show these identical trucks under them. I am going to guess U.P. rebuilt these smooth riding trucks with different oak top beams as they transferred them from older non-standard cabooses to the steel CA-3's and CA-4's. I believe it would be easy to modify the 3-D model to get an exact U.P. "Q" truck since all that needs to change is the tops of the coil spring mounts and the nut and bolt details on the outsides of the top oak beam...and maybe make the top oak beam just a few thousandths taller. Drawings and photos are available. 33" Fox Valley narrow wheelsets with Micro Trains axle lengths fit perfect with no problem and look fabulous! I'm giving these five stars!! Bob Gilmore (robert3985@aol.com)