For those folks wondering what I'm on about.
Here's a Weihrauch 25mm seal arbor :-
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Here's a TX 25mm seal arbor :-
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And here are the two arbors for comparison :-
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As you can see the Weihrauch seal arbor is bigger than the TX arbor which enables me to machine the Weihrauch arbor down to the size of the TX arbor and use the TX seal which is 4mm shorter than the Weihrauch seal.