Well
I can provide some answers that question,
I now have several types of the dish's for DirecTV and Dish TV brands, dump guy is my friend and helps a lot.
I have been looking for and making the smallest dish possible for the RV, and have found that the brands WILL NOT interchange, the backing plates/LnB arms etc are of different hole spacings, lengths and width's etc.
I did find that you can countersink the bolt holes for attaching the backing plate etc to the dish/reflector very easy. Just ask if you want the info.
I mounted the Direct TV backing plate on a small round Dish brand reflector and it looks like the factory did it with the countersunk bolt holes etc.
You have to MAKE sure that the LnB arms are the SAME length,(every brand or size has/is different), the Lnb head sets at the same angle/degree as the OEM equipment did, and the dish/reflector has the same depth/angle as the OEM dish etc.
I started with the older Multi-satellite dish and then mounted the 3 angle screw adjustable head (from the Slimline reflector/dish)to that dish using the DirecTV dish/reflector, seems to work perfectly, and I have all the finest adjustments possible.
I was given a Slimline DirecTV dish and it is very large as compared with the Multi-satellite dish.
I am looking for a smaller round/oval dish/reflector that will work with the DirecTV LnB SD head.
Hope this helps,
Tia,
Don