Hi All, Sorry to hear your not on the road anymore Chris but great that you can share the knowledge still!
the problem is the diff CSR is bolt in and the ASU push. not realising this when i had the CSR box rebuilt i used the CSR diff. i have had the ASU transfer box rebuilt and modified to use the bolt in drive cups by Martin Emment of Gas’n’Gears (HotGolf) from the GTi forum. as it was cheaper than opening up my rebuilt bos and swapping diffs.
here are some pics.
ASU Transfer box with collar – this makes the length of the shaft correct
length of shaft coming out original ASU TB
length of shaft in original CSR
difference in case ends of ASU and CSR which causes the shaft length issue.