I have had the following different feednecks;
Standard Non Clamping fixed
Angel 04 (I think)
Angel 06 Speed
Angel A1
CCM - Imported from America
Standard Clamping one on current body
With all the above I felt that the best fitting ones were the CCM and the Angel A1 - If you post up for a A1 type you will probably find one of these easier than a CCM.
You will also find that the Detents on the body are also Angel Thread.
As for cross threading, be very VERY careful when your screw it together, make sure its properly lined up and dry fit before using Blue Locktite.
Hope this helps
Phil