now i have to reinstall all my plugins for 64 bit RB - which is the best version when i have the choice? some come in two types - 64 bit or 32 bit is easy but what about 2 or 3?

When they work I always choose VST3. Sometimes VST3 doesn't work for whatever reason. When a VST3 doesn't work, I use the equivalent VST2.

VST3 is a newer specification than VST2. VST2 development tools are depreciated and have not been supported for a long time.

thanks Jim, when i have the choice i'll go for 64 bit vst3 as a first step

RealBand 2021 supports 64-bit VST2 plugins. It does not support VST3, though it certainly doesn't hurt to install those too if you have other audio programs that you want to use the plugins with.

thanks Simon. something at the back of my brain suggested that vst3 wasn't supported

You're very welcome Bob, that's what I'm here for!