If you're going to a machine shop may as well just have the tool made. It's a pretty quick and quite easy job and aluminum would be just fine.

I don't think any of the rubber ideas are that good, may help some, but an accurately turned metal guide will be far superior.

I forget the installation tolerances for rubber lip seals, but thinking they are much less than you'd guess. And I'm sure for a long seal life no run-out is best.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-