Following the manuals (yeah, you should too) on how to import .obj 3D models, I created 2 mods.
Both models come from NASA:
Extract to addons.
It will add 3 objects, the complete HDU (2 modules) and each module if you wished to use them separately.
Here is screenshot with those 2 objects and an ESA and a NASA astronauts from DoctorofSpace's Mod Emporium.
I hope you like them and any feedback is welcome.