Sometime in HJ the longer pitman arm was introduced p/n 9935626 which gave you 25:1 steering with the original HQ 20:1 steering box. HQ 16.7:1 became 20:1. This stayed the same for HX and changed in HZ when the 20:1 box (old 16.7:1) was dropped.

Steering arms are different story though. HQ used the same arms for power and manual steer (p/n's 2809480-81). HQ-HJ 1-tonner had different arms for some reason (p/n's early 2825250-51 and later 9931737-38) used for both manual and power steering.
HJ introduced the longer steering arms for manual steer 25:1 ratio (p/n's 9935665-66), HOWEVER GTS retained the original 16.7:1 steering and HQ shorter arms. Power steering retained the original HQ steering arms. At HJ release though HJ was the same as HQ (ie same arms for manual and power steer).

Nothing really do do with RTS.