Disco 2 Climate retro fit

Well after a brief excursion to the dark side (BMW) I'm back with the green oval and bought a mkII. It's a bit poverty spec and needs a few upgrades starting with climate control. At present it has the manual control heater and that's it. My question is, how many types of heater box are there ? Standard, standard with aircon and climate ? I can only seem to see 2 types on our favourite auction site.
Oh and yes I know it would be easier to buy one with it already fitted, but where's the fun in that ?

Just the two, "climate" gives nothing more than automatic control on the standard AC system.

Lovely, thanks for the info. Parts don't seem too pricey so I can feel a "how to" coming on...