I think though in the UK at least they were called off-road and had a model called pro-flex. After a while in the early 90's they became known as proflex, around 97ish they were in financial difficulties and were bought out by K2.
I never heard of any.........I always thought that K2 acquired Proflex to expand into the MTB market..........if it is Offroad Proflex ye are after, IDriders is the best place http://idriders.com/proflex/smf/index.php?board=1.0
<edit> just had a thought- Raleigh used K2 tubing in 1991, dinnae ken if that's any help?