is this not a good leak.....

after draining the gearbox and rearend and refilling it fresh gear oil, I wiped down all the surrounding areas that had grease, oil and gunk. After taking it for a good 30-40 mile spin, it sat in the driveway for half a day until I pulled it in the garage. Walking out the garage I notice a puddle of oil right where the gearbox was. I laid down next to car and I could see it leaking where the bellhousing mates to the adaptor plate. I'm assuming it has been leaking for the 2 years I've been driving it. Is it a great concern that its leaking in that area. The clutch seems to be fine and not slipping so I dont think it's leaking so much its effecting the clutch. Big concern or little concern? It seem to be gearbox lube and not engine oil.

Gear box lube leaking around the input shaft seal -- not getting on the clutch -- is of little crucial importance except for one thing: Don't let your gearbox run dry! Check the oil level from time-to-time.

Ok....I wont ask how hard it is to change the seal, cause i know it depends on your ability. Looking at the workshop book I guess this is easier than the rear engine oil seal. Can the tranny come out through the inside of the car or does it have to drop from the bottom?

The tranny comes out through the interior. There is another place the trans can be leaking from in the front. There is a small plate and gasket that holds the laygear shaft in place that could also be leaking. It is below the input shaft seal. Either way, the tranny would have to come out to repair.