Someone noted on Seibertron the other day, that the Japanese Legends versions of Misfire and Slugslinger, have their waist/crotch pieces swapped over (JP Misfire has TR Slugslinger's crotch, and JP Slugslinger has TR Misfire's).
I guess they are exactly the same to fit with either toy, and just have some surface resculpting on them... so I wonder if there was a reason why TakaraTomy decided to swap them around.