You get 4 razorbacks and 4 turrets but since the heavy bolter and lascannon turrets are different you can essential only make 2 of each.
This differs from the GW website picture where they show you 4 heavy bolter razorbacks. So if you assume you get what you need to make the picture you are wrong. For as much as they charge for these now they should include 4 turret sets.
Here they are assembled. One thing that is interesting is that the turrets are forward mounted compared to the more back position in 40K. This is interesting since the whirlwinds are back so they essentially had to do a different mold for this arrangement (might be standard predator mold I have yet to get any of those).
Some people might be wondering why anyone would be posting the contents of old blister packs on a blog. One of the reasons we can see is right here as what you might think you get and what you actually get are different. You cannot ask GW what is in these packs as the customer service people have no idea. I tried that with the space marine character pack. It took warseer like 1 hour to tell me exactly what was in it while GW via email never got the correct answer.