Thanks for the help and suggestions guys. Ken you're spot on. I just re-named the 3do and what you get is a wet Nurburgring without the wet appearance. Mind you, for those not familiar with 'wetnurb' and 'wetspa' it doesn't look that wet anyway until you add the falling rain 3do files. And, as you predicted, the falling rain disappears with the addition of the Kelllaaa 3do. It's just like driving on a dry version of the nurburgring only the tyres don't squeal, scarcely change in pressure or temperature, and, of course, you'll go flying off the track if you try to take corners at dry speeds!
It's a shame because I was trying to set up a realistic '66 season with wet races at Spa and the Nurburgring. Wet Spa works great, but the nature of the Kelllaaa add-ons means that the wet Nurburgring probably isn't gonna happen. And I won't try and do without those Kelllaaa graphics, they're incredible! I will try and locate that program that unpacks 3do files and see if I can sus it out, but I'm now starting to enter GPL modifying territory that's out of my league. It'll be interesting to see if I can get it to work and I'll certainly let everyone know if I can.
Incidentally for those who haven't tried the wetnurb and wetspa circuits with the falling rain add-on, I highly recommend them.
Wetspa is downright scary! Maybe the tarmac texture could have been altered to look shiny and wet, etc, but overall it's great fun, and looks plenty wet enough with the falling rain graphics. I think they've been around long enough to be considered 'old news' but they're still great fun.