ARAH and Newsculpt are essentially the same thing. The only real difference is the plastic rivets on the newer arms. However since they are consistantly classified as their own thing I'll list them seperately.
HeadsARAH: Fits Newsculpt bodies with little or sometimes no mods, needs to be dremeled to fit 25th neck
Newsculpt: Fits ARAH bodies with little or sometimes no mods, needs to be dremeled to fit 25th neck
25th: Needs some sort of filler piece to fit ARAH and Newsculpt bodies, completely different design
TorsoARAH: Fits Newsculpt heads, arms, and waists with little or sometimes no mods, fits 25th arms with little or sometimes no mods, 25th heads need major mods, has back screw and seperate waist
Newsculpt: Fits ARAH heads, arms, and waists with little or sometimes no mods, fits 25th arms with little or sometimes no mods, 25th heads need major mods, has back screw and seperate waist
25th: Fits ARAH and Newsculpt heads with neck dremeled off, fits ARAH and Newsculpt arms with little or sometimes no mods, no backscrew, attached waist
ArmsARAH: Fits Newsculpt and 25th torsos with little or sometimes no mods, riveted solidly together, must be cut or rivet punched to seperate, none have swivel wrists
Newsculpt: Fits ARAH and 25th torsos with little or sometimes no mods, can be popped apart, some have swivel wrists, upper and lowers interchange with some 25th with little or no mods
25th: Fits ARAH and Newsculpt with little or sometimes no mods, can be popped apart, most have swivel wristsm upper and lowers interchange with some Newsculpt
WaistARAH: Fits Newsculpt torsos and legs with little or sometimes no mods, fits 25th legs with little or sometimes no mods
Newsculpt: Fits ARAH torsos and legs with little or sometimes no mods, fits 25th legs with little or sometimes no mods
25th: Attached to waist not swappable with older styles, fits ARAH and Newsculpt legs with little or sometimes no mods.
LegsARAH: Fits Newsculpt and 25th waists with little or sometimes no mods, uppers and lowers interchangeable with Newsculpt and some
25th, other 25th need mods
Newsculpt: Fits ARAH and 25th waists with little or sometimes no mods, uppers and lowers interchangeable with ARAH and some 25th, other 25th need mods
25th: Fits Newsculpt and ARAH waists with little or sometimes no mods, uppers and lowers interchangeable with some Newsculpt and ARAH
Also note that NOTHING is an absolute fit. There are different sized neck balls and arm sockets throughout every line and some mods may be neccesary no matter what parts you are using.
Hope this helps

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Joeczar wrote:
The bodies used for the HOF figures are much like the GIJCC itself, old, rigid, and unmoveable.