Thanks,
That makes it a lot easier for me now as I already have a JT 17T front sprocket (750x DCT uses 17t instead of 16t on the 700x DCT) so ordering the rear sprocket and chain will be straight forward.
Thanks for your input chaps.
Spoke to Busters this morning. They gave me their part numbers and all ordered via the website.
FYI the part numbers for an X DCT are
112 link endless chain 748.01.85
16 tooth front sprocket 726.01.12
39 tooth rear sprocket 727.33.06
Works out at £107 delivered by DPD courier.