I change them when some still have journal boxes on a fairly modern car. Also, its a way to convert couplers and get a better truck in some cases.
Thanks everyone, great replies.
I only have a few cars at this point but was thinking about standardizing now before I get so many that it would cost a small fortune to replace them. One issue I have been reading about on replacing wheelsets is axle length.
If I use trucks from the same manufacture, Kadee or P2k, would there still be the axle length difference on each truck?
Modelling in N scale, I still find some rolling stock that doesn’t come with knuckle couples or have knuckle couplers that aren’t functional. In these cases, they get replaced with MicroTrains trucks immediately.