Ive got a feeling mq chassis are a bit wider, gq narrower for coils - i haven't personally checked that though, just heresay
Bonnets are interchangeable,
doors are, but mq has quarter window and gq doesn't, gq also a lot dearer.
gaurds from early leaf cab gq ute are same as mq (not flared)
flared gq gards can be put on mq - but need gq grille also and some minor mods,
have a look at my link ive got gq flared gaurds and grille on a mq, might put doors on it also in a month or so, or maybe fix the std ones - cheaper
Mick