it seems to me uniting them will only make texturing them even harder from the look of them they're some sort of engine and will have lots of little parts ... (thats a double shrug from me) ... tho here is a bit of something if it is of any help ... boolean will not work if the objects do not completly intersect, and boolean sometimes will not work when the geometry gets too complicated (keep in mind that a lot of maths will be done to work out how to mesh the geometry) ... when all else fails, and if you truleey seek to unite them you could use Poly>Combine. then Poly> Merge Vertices. ... Wow, what a lot of geometry, ... thats a nights work and a sore head