It's never easy to identify a second hand-Inferno, as any of the parts could have been changed by the original owner.
All of the MP-7.5's are visually quite similar, but the main differences between the Kanai's are:
Kanai Worlds Edition: Gold coloured wheel hubs with blue nuts, TCD diff front and centre, turnuckles, universals all round, quad brake, ballraced servo saver
Kania 2: As above but, gold turnbuckles, fuel splash guard, 3.5mm shock shafts, blue hubs and nuts, slotted brake discs,
Kanai 3 As above but, TCD front diff only, lightened chassis with milled out portions, twin thick brake disc.
Obviously lots of other differences (shock towers etc), but difficult to spot by the untrained eye.
Hope that helps.
If you post a picture or a link to the picture I'll definately be able to help you.