Oh wow...this is gonna take some explaining.
ALL Grand Nationals had a WE-2 designation. The WE-4 was a special "T-type" or Turbo T. It came in only black like the Grand National, however the WE-4 had chrome bumpers instead of the GN's black ones.
All Grand Nationals had 3 "Grand National" emblems. 1 on each fender and one on the truck lid. they also all had 3 3.8 SFI Turbo emblems. 1 on each side of the turbo hood and one opposite the gn emblem on the trunk lid. Alot of people like to remove the 3.8 SFI Turbo emblems for a slightly cleaner look. The Intercooled emblem on the 86 and 87's was only beneath the fender emblems not the trunk emblem.
the Grand National was a special edition t-type, not the other way around. It was made to commemorate the Grand National racing series in Nascar.
The T-type or Turbo T was a regular regal with the same motor as the Grand National. If it is a T-type it will have a T-type emblem on the fenders. If it is a Turbo T with will have a rounded square with a little red T. 84-86 were t-types, 87's were turbo t's. there was no difference in performance other than between the 84, 85 years and the 86, 87 years.
The WE-4 was like i said, a black car, like the grand national, except with chrome bumpers. they wont have any emblems on them at all. They had a very clean look. No difference in performance between any of the cars untill you start getting into the GNX.
The GNX had the same motor and same turbo although the turbo was slightly modified. More boost, different tune, and a very complicated suspension setup that worked amazingly. ASC Mclaren Modified regular Grand Nationals to make them into GNX's. The GNX had 1 "GNX" emblem on the grill and one on the trunk lid. It had fender flares, and functional fender vents. They were about 6-8 tenths faster in the Quarter mile and was the fastest production car untill 1990 when the ZR1 came out. The GNX also had a kick ass guage cluster over the regular grand national and ttypes. it was the grand national to end all grand nationals.
If there are anymore questions just let me know