[JFP in PA]

An "IMS" is the rear bearing on the intermediate shaft (visit LN Engineering's website for the lugubrious details), the “RMS” is the engine's rear main seal around the crankshaft, early cars had a tendency to develop mild to severe oil leaks to the level that would destroy the clutch over time, requiring replacement.

Do some searching, you will find more than you ever really wanted to know on both subjects......