Peter, that's excellent info but it throws a spanner in the works!

I will check the code on the 6Y/GY tomorrow morning. Will it have 91mm flanges? If so that's even worse as I had the driveshafts for that gearbox reco'd with new boots and all that. But they'll be no good on the ACD box if I use it, right?

What are the main pros and cons of each gearbox? I assume the ACD is significantly better? It's being cleaned up and put back together with new carrier bearings this week, but I was hoping to put the 16V into the yellow car tomorrow, which I can't do now if I should be using that box and not the 6Y/GY or whatever it is.

I'll get a picture of the mount, but from memory they were identical to each other.