TartanRed wrote:
Flash, I have seen a four synchro gearset fitted to a 3 synchro case, but it was a major engineering effort by a skilled toolmaker/engineer who essentially did it for the challenge in his own fully equipped fabrication workshop. It would not be cost effective unless you could do it yourself... For example, a large chunk of the centre gearbox web had to be removed/remade from memory in order to accommodate the heftier gearset...
If you want a four synchro box and magic wand change, it is pretty straightforward to mate an 850 diff housing to a four synchro box - I have one in my 850 and it works very nicely. An unworn direct 850 gear change is quite positive, with less linkages than the Cooper type remote housing (eg additional wear points).
I've done the same, 1100S, 4 synchro box, 850 diff housing. Car looks original inside, just don't open the bonnet