Widman is a cool dude but has somewhat obsolete data in this paper as do some of my white papers (which needs updating).
We need to context this paper. I believe Mr. Widman (and he can correct me if necessary) wrote this about the time that some manfactureres were recomending that synchronized Manual transmissions (especially Honda) should be lubricated with motor oils such as 5W30's etc. About the same time MTL's specifically formulated for manual transmissions were appearing on the market. So there was confusion about what MTL fluids should be used.
To clarify a couple of points, the GL-4 wear protection rating for MTL's came mainly from a combination of ZDDP and sulferized, buffered olefins, and not from a Sulfur-Phosphorus (S-P) "Exteme Pressure" additive package used for differential lubricants.
As explained elsewhere in other White Papers on Manual Transmission Lubricants, the Performance Improvement (PI) package (additive package) for synchronized manual transmissions also contain a host of other chemistries for shift improvement (specialty friction modifiers), rust prevention, metal inhibitors, emulsifiers for moisture intrusion, etc.
In many MTL formulations of late, you will see lower phosphorus levels (anti-wear), and very low levels of zinc. The low level of zinc will come from a low treatment level of ZDDP for anti-oxidant purposes only. The phos will be one of the anti-wear components. The other anti-wear components will not be detected in a conventional VOA.
Early on, the only available application specific MTLs were 75W90 or 14.5 cSt lubricants. Later, due to cold weather shiftability problems, Texaco, GM, and Pennzoil brought to the market the 5W30 or 10.X cSt viscosities.
Since the time of his writing, there has been a host of new transmission designs and formulations brought to the market.
For a list of current application specific, GL-4 MTL's of various viscosities, see the last post here:
Paper on Manual Transmission Lubricants