Manual transmission/Differential fluid change: how difficult?

[rino]

My mechanical background for car-related work is limited to just one engine oil change, which I performed yesterday. Naturally, I wish to avoid opening the proverbial can of worms and ending up with more on my hands that I can handle...
I have a Haynes manual (Diesel 123 Series) which describes very poorly both fluid changes in less than half a page; besides, most of the images shown do not match the items and locations for my specific model (1979 240D). Are there more precise instructions/images I can view online?

I have wooden ramps which will raise my vehicle 4" evenly from the ground and enable me to go underneath to do the work. I would like to know what special tools I need to have in order to perform these fluid changes (special wrenches, pumps, etc.), what type of fluids are preferable for my particular car model and, honestly, are these maintenance tasks within the reach of a beginning DIYer like me?

Thanks in advance,

Rino