hi all first time on a forum,

i was wondering whats the difference between the 423b rear diff and the 219b rear diff. the 219b is the original in my car but i purchased the 423b which was advertised for the uk99. i didn't know the original one in my car was a 219b until i had taken it out to change it. the problem is i am having trouble locking the left driveshaft into the diff. i'm not sure weither its just that the locking ring is missing or its because the diff is different and i need the drive shafts to fit the different diff.

please help!!!