Won't be a massive problem if you're buying in pairs.
Check on your compliance plate, if your axle code is CA46 then you'll be sweet, anything else and you need to look at finding a different worm and gear to correct your speedo.
If your code is HG##, then I'd check the diffs being sold and if the rear is a C200 (salisbury type diff, ten bolt inspection plate), then stuff that, stick with what you've got, and fit a second hand airlocker out of a Patrol.