Well Rich. I just crawled under the truck and guess what... No adapter in place whatsoever. My speedo cable plugs directly into the T-case.
I was going to pull the driven gear and see what I have, but I do not have a 1-1/16" socket as it appears the size of the driven gear holder is. I have no interest in damaging the holder trying to remove it with the wrong tool.
I will borrow a socket from work and pull it tomorrow to see exactly what I have.
From what I have been able to learn, and according to this page there are only 5 different size 205 pencil gears available, ranging from 18 to 22 teeth. The pencil gear is the one I was attempting to remove, right?
They also say I can only have 1 of 2 possible output shaft gears. An early metal type with 5 teeth, and a red later one with 6 teeth.
Here is a link:
http://offroaddesign.com/NP205Tech.htm
So, since we probably cannot calculate what ratio adapter I need without knowing what drive output shaft and pencil gears I have, to be continued.....