I tried the Khajiit tail replacer and it was spazzing/floating. I also tried ShadowsandDust's alternative xml without luck. In order to fix it, I drastically decreased the spring constants and spring damping values for the constraint limits of all tail bones. I also changed the collision from Body, Tail to Body, Legs for each of the rigid bodies (the constraints generally prevent self-collision anyway). My HDT version is 14.28 and so far I've not seen any spasms and it acts nicely. I've added my edited xml as an attachment. If anyone else suffered from these problems, give this one a go, and let me know if it helps :-) hdt_tail_khajiit_xml.zip
