I've tried loading Sampletank 2 instruments in Sample Tron / Sonik Synth but unfortunately just get the message 'This is not a Sample Tron / Sonik Synth Instrument' so cannot be loaded. Tried loading them in ST 3 Free but that didn't work either - though I may not have the latest ST3 Free - will check that now

Sampletank 2 instruments will not load in anything other than Sampletank 2 or 2.5. They can be imported into Sampletank 3 using the import legacy instruments function however. Sonik Synth instruments can be loaded in Sampletank 2 but not the other way around.

JoeGBradford
I've tried loading Sampletank 2 instruments in Sample Tron / Sonik Synth but unfortunately just get the message 'This is not a Sample Tron / Sonik Synth Instrument' so cannot be loaded. Tried loading them in ST 3 Free but that didn't work either - though I may not have the latest ST3 Free - will check that now

Again, it's been awhile, but I'm pretty sure Sampletank has to be the "master" program (You can load the other instruments into Sampletank, but not the other way around).  I used to access Miroslav and Sonik Synth sounds from inside the Sampletank interface.
 
With ST3, I'm not if you can directly load the older libs -- you may have to import them first.

Thanks - got the latest version of ST3 Free and importing ST2 files at the moment - fingers crossed!!!

You have to import ST2 into ST3, but it's pretty painless except for disc storage.
 

Yep - appears to be working :-)  Presumably I will lose the ST2 multis and effects but I can live with that to get the sounds back especially Miroslav
 
Thanks for the help here - made an old man very happy!