Well what can be said, when changing my drive shafts I found 1 oil seal needing to be replaced "total pig of a job" driver-side drive shaft must be fully removed. To make lief easier removing the exhaust gives you slot more room to tap the new seal into place, luckily I've a aftermarket exhaust & removed a single length
(original exhaust is a 1 piece item so it could be slot more fun)
Before you start putter new seal in the freezer overnight "no joke!"
Remove the old seal... don't touch the edges the raised centre hit with a chisel/screw driver etc the outside edge,, the entire area you can see, this helps pull the seal from the aperture once it's nicely hammered you should be able to lever the old seal out.
Clean up the side walls & apply a small amount of grease.
Get the new seal from the freezer & quickly add grease around the outside edge..
Place the seal against the aperture & using either a large socket (equal size to the outside edge of the seals body) or like me just using a 5lb hammer just tap the seal into place (if it's totally square it'll slide in) a couple of taps later & it's done.
Replace everything drive shafts etc then test the seal with new gearbox fluid.. make sure no leaks etc then tighten it all up "job done"
Anyway it's working a treat.... just take your time if it's your 1st time doing this on a mini as the space is very limited & very awkward.