I think Mepiston wisely brought this up !?! So I thought I'd start the list for the Humies, and then see what you all can add for them or the other aliens in the ranges !
Some are obvious ! Valiant APC = Rhino ; Jackhammer IFV = Chimera or Razorback ; E/W Half-track = Rhino, Add a turret from the E/W 6 Wheeled APC = Razorback. The same can be done to the Valiant to make it a Razorback. Intruder = Griffon ; Atk Chopper = Vulture ; Cgo Chopper = Valk. Firewall = Hydra ; Petard = Whirlwind/Manticore/Hunter ; Thunderstrike = Basilisk ; Ramjack wheeled APC = ? Mammoth Hvy Tank (looks like a Tiger I !) = Ragnarok ; Cruiser Lt. Tank = Siegfried ; Bastion & Chasseur = L/Russ, Predator ?!?! Jungle Troopers = Catachans (??!? ) ; Industrial Inf. = DoK ; Any of the DRM or E/W Human inf. can be IG or Traitor/Chaos Cultist troops. E/W Khazari = Squats (???! 
) ; E/W Prefects = Arbites ; E/W Khazari wheeled APC = Sentinel variant ? My thoughts ... your turns ! 