In the current Epic space marine lists, Razorbacks are the bomb for additions to mechanized formations. Normally as part of the cost for a tactical formation of 6 stands of infantry you get 3 rhinos as transports. You can then add a razorback to it for like 1/12th the cost of the formation. Since it only has capacity for 1 infantry stand you do not lose a rhino so you added a little more punch and extra transport capacity for very low cost. You can add another but then you get 1 less rhino so this is not often done.
These old razorbacks are on classic rhino chasis with a lot of extra components on them. Stowage and extra armor.
Here is a close up that shows the classic external gunner with his lascannon-plasmagun turret.
The previous owner of these, lost one of the turrets so I used that one for a more stylish Hunter. Extra armor to help protect it from all that additional fire it will take. Ofcourse no in game affect. It worked out since the plastic rhino I modified to formerly hold the Hunter turret now has a spare whirlwind turret on it which rounds out my second unit of classic whirlwinds.