Ott, they are talking about the friction material (aluminum vs steel) that is housed within the first gear. This is what is used to slow the 2 nd gear syncro ring. I have only ever seen one that was worn enough that warranted replacement out of a dozen or so transmissions that I have worked on this last year. As far as I know the friction material is unavailable by itself necessitating replacing the entire first gear if needed.

Steve
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Last edited by sstock; 10/16/2019 12:28 AM.
1953 Chevrolet 3100
261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done
In the DITY Gallery
Video of the 261 running

1964 GMC 1000
305 Big Block V6, sm420, the next cab off restoration