I took another look at the 2.17 version sun gear thrust mod
for the Ross and it occurred to me that you will have more thickness
available  for the sun gear thrust bearing if you limit the needle
bearing diameter to 2.187 inches instead of 2.5. That allows
the needle bearings to partially fit inside the fixed planet 
gear housing.  This gives a needle bearing stack length 
of over a 1/2 inch. The dynamic load capacity of the
smaller bearing is hardly affected as the limit speed
goes up to 7700 from 6900 RPM. Static load rating is 
only 23,000 pounds instead of 26,900 :)

That means a bit more grinding on the sun gear from 1.75
OD to 1.5 OD. 
  
Paul Lamar
 
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