I wonder how many Tralla, Metralla, Campera, Sherpa N models etc etc which were all earlier Bultaco models 59-64 and some still made into the 70's were actually modified and trialed during the contentious period. Probably some....
Same with Montesa and Ossa. I've fairly recently seen a couple of rather nice looking trialised Impala's and one 160cc Ossa around the net, all fairly modern conversions though. In my eyes far more interesting than say a Trial Bantam or the overly popular cubs.
Wayne....