Well its only the flange bolts you have to remove to get the shafts out takes a couple of minutes max, shafts you have bought are the later design the ones you have fitted are earlier, not sure what year they changed, but my 93 has the later type, mates 87 has the earlier type like yours.
PPs you dont need to change them to cure a leak its either the gasket or the rubber cap, both are peanuts.
No need to change or touch the oil just jack up one side at a time
Lynall