In addition to the capacity, you will also want to find the length of the axle and the spring center. The hub face to hub face measurement is how you determine the length. If you can't find a spring center length that matches, it is possible to cut off the spring seats and weld on new ones with the correct measurement. I have attached a video below showing how to measure.
For example, the Trailer Axle with Idler Hubs # e84YR you looked at has a length of 60" and a spring center length... view full answer...