Hey people, me again!

I am thinking of chaging my clutch and universal joints in my 740 non turbo, how hard is it to change it yourself? Does anyone think that the center bearing would need replacing? i am starting to hear clunking from the tail shaft, when reversing, etc, and really hoping that it is the universals.......it should be, right? *crossing fingers*. How heavy is the gearbox? I mean, i'd prefer not to be squashed under the car if i can avoid it...... Any way, any input would be GREAT!

p.s. i wanna do it myself, because i have been quoted $450 aussie dollars for JUST the labour! Clutch itself was something like $280 aussies ones