LT230 oil seals

I've noticed an oil leak from the front drive shaft output on my 90's transfer box, which obviously needs fixing. What's the best way to go about this? The obvious approach is to work from underneath, but would it be easier to remove the floor panels and work from above? Or even to drop the gearboxes and do it on the bench, along with all the other seals while I'm at it.

There's no trouble with the LT77 main gearbox apart from the usual 2nd gear grinding when cold, but the clutch age is unknown.

It's a 30 minute job if you slide underneath. Why would you want to create more work for yourself?

Corteco seals are decent and new flanges are as cheap as chips and will give a decent seal surface

Yep piece of **** from underneath.

Did the seal, bearing and shaft on my transfer box from underneath.