LOL, just found all this out too and got back to the customer.
With the TC3 diff discontinued, what to do is buy the 1728 and then the TC3 outdrives which is an expensive way round it.
As an alternative there is a Yokomo one way diff designed for the TC3 and is still available, its Part no. SP3938-6. So the customer is returning the 1728 and we're ordering the Yoke version for him.
Soooo, concluded!! cheers guys
