Mmmm ...
Brian .... vaguely remember discussing this very question (soooooo many) years ago with a mate who was Ex 161 Recce.
Apparently when ordered the CA32 (B206B1 Kiowa) the powers that be decided the beastie should come with the 'LongRanger' M/R blades and this then required the longer LongRanger T'boom as well and the slightly upgraded engine, Tailrotor and T/R G'box.
I believe the T/R g'box and longer T/R blades required the ratio change in the Xmsn (was prob also a LongRanger M/Xmsn .. I don't really know?)
At the time of said discussion we were also comparing the merits of various alcoholic beverages so accuracy of memory storage unit is doubtful ?? I would be happy to be corrected on the above blurry data???
BTW kindly say 'Hi' ... to Ross M if you happen to see him ... Cheers