This pack is an optional add-on for the SSTU mod (here) that adds SSTU functionality to some third party mods, a M-1 engine (modified J-2 model) and a Skylab station core (these last two only needs SSTU). This only includes config files, no other assets are included yet. The mod packs modified by this pack are optional, the only dependency is SSTU itself. Here's a list of what's included from each mod listed: SSTU: Skylab-alike Station core, second Apollo SM variant with swap-able