Pershing IB and Pershing II RR
Pershing IB was a single stage, reduced range version of Pershing II with the same range as the Pershing IA. The Pershing II launcher was designed so that the cradle could be easily repositioned to handle the shorter missile body. The intent was to replace the German Air Force's Pershing IA systems with Pershing IB, since SALT II limited the range of German-owned missiles. The Luftwaffe agreed to destroy its Pershing IA systems when the U.S. and the U.S.S.R. signed the INF Treaty, hence the Pershing IB was never deployed.
Pershing II Reduced Range (RR) was a follow on concept that would have modified the launchers to hold two single-stage missiles.
Read more about this topic: MGM-31 Pershing