They all leak oil eventually!!
Before you fit the new seals, check that there is not too much wear on the side cover bronze bushes, too much "slack" allows the output shafts/potjoints to bounce up and down, which wears the oilseals out very quickly... If their worn either fit a better/good secondhand cover, or I've got brand new Rover ones in stock, part number CHM 85 at £15.00 each plus p+p......
Check theres not a groove worn on the potjoint to seal face, that will make them leak..
Make sure you fit the watershields to the potjoints before you refit the shafts, or else road dirt/mud etc chews up the new seals very quickly...
Seem to remember it's a 4.1 helical CWP, centre oil pipe, few of my "special tricks" etc.......
Cheers, wurzell.