I have a DTV dish with 3 lnb's. There is an area for the two other lnb's. Can I put the other two lnb's on this dish (Slimline) and if so, where can I purchase them?
I'm guessing you have a Slimline with 3 LNB heads. In fact, there are 3 LNB assemblies inside one head. No need to worry if you are getting all the channels you are supposed to.
The 3LNB assembly for the Slimline is much smaller and there isn't any place that looks like it could hold more. The 5 LNB assembly has the 99/101/103 head in the center and the 110 and 119 to one side. The blank space on the other side is either there for symmetry or it holds some of the switching circuitry.
There was a 3 lnb kaku out that just removed the horns for 110/119 but kept the same shape, it was quickly redesigned though to remove the "wings" to save money.