The short answer is nope no one sells one,
the tricky part is at least on the 51 the spindle isn't a size that is used on standard bearings.
You can get around that problem by making a bushing or sleeve, not hard to do if you have a lathe or a mill.
The other thing to consider is how the seal will fit.
Can be done with just a little machining.
The good news is the cups that fit in the hub are a standard size.
Maybe Whitedog will chime in with some timkin numbers.
I used 1280/1220, 2788/2720 and 55x80x8sbrm.
That will get you in the right neighbor hood in the timkin catalog, then it's measure and pick one that will work for you.
