^^ maybe he's talking about the rear diff when referring to the rear end?
Also G you need to be specific about the 'RS' you're talking about as there isn't just one particular model 'RS' and that's it. As I've said time and time again, RS and Evolution spec keeps getting confused with people referring to Evolution specific parts as RS parts when the reality is most RS models carry the same parts as the non-RS models.
If you are talking rear diffs, let's break it down this way - RS can be 4WS (E39A) or non-4WS (E38A).
- E38A models before October 1989 build date will carry the 3.545 rear axle ratio 1-way plate type/mechanical LSD along with three bolt axle flanges while October 1989 onwards will be 3.909 ratio with four bolt flanges and a 1.5-way LSD.
- E39A models before August 1990 build date will carry the 3.545 rear axle ratio viscous LSD and three bolt axle flanges while August 1990 onwards has the same viscous LSD but now with 3.909 ratio and four bolt flanges.
Evolution model Galant VR-4s (ie they are ALL August 1990 onwards build with 5 speed manual gearbox) will carry the 3.909 four bolt rear end with the only difference is the E38A RS Evolution will have the 1.5-way plate LSD while the E39A Evolution/RS Evolution (with 4WS) will have the viscous LSD.
So really, an "RS" diff can be any of four different combinations and not one particular type.
Part numbers from CAPS/ASA for further reference if needed:
MB393808 3 bolt axle flange
MB569618 4 bolt axle flange
MB393069 1 way plate LSD
MB664374 1.5 way plate LSD
MB664107 viscous LSD
If of course you are talking about the rear bumper, then the RS rear bumper is no different from any other JDM VR-4 rear bumper, or any JDM 6G Galant with the full plastic bumper for that matter (bumper cover of course, the frame support differs between 2WD/4WD).