I have lots of modifications that you can carry out on your Stag to improve the reliability of your transmission. For example a reconditioned differential with a brand new 3.45 ratio CW&P, new bearings and reinforced nose (they break!), together with my brand new GKN drive shafts (which also improve the handling). By the way these shafts also eliminate the infamous 'Stag Twitch' as well.
PLEASE do yourself a favour and DON'T waste your money on so-called 'reconditioned' drive shafts. The splines you will get will be 25 years old and, with no means of greasing them, the splines will have 25 years of wear from being used for all that time with no lubrication! They will be worn to hell and gone. ALL you get is new U/J's which in themselves are fine but with the worn splines are a complete waste of money.