From what I've read here in past threads, at least some of the
trailers used the same bearings as the
trailers, which are L68149 inner (1.378 in/35mm ID), L44649 outer (1.063 in/27mm ID), and an RG06-050 double-lip seal (1.719 in ID/2.565 in OD). I couldn't say what your trailer has, so I might suggest you open one up and get the number off the bearings. Don't forget you need the outer races, too, as if you trash a bearing, it'll take the race with it. They are usually sold as a set anyway.