Falcon from Halo:Reach

http://wikicheats.gametrailers.com/images/9/95/Halo_REACH_Falcon.png

and if possible try to make the grenade launcher body grouped to the Regular turret.

Sorry to bring down your hopes, but most Reach models don’t and never will (for a long time) exist. Porting models from Halo Reach is only in the hands of a couple of people as of right now, and it has been like that for quite a while.

Well that sucks