Hello!
How would I convert a .spt file to a .obj so I can export as .nif? I looked around and can't find a old version of Speedtree anywhere and the version I have is v7 which doesn't support the older .spt file.
I have about 17 .spt Trees that have to be converted to a .nif! Need Help ASAP! 
Actually the simplest thing (and our workflow, so I can't advise on anything else) is getting MAX into the process, exporting from speedtree to MAX and from there export to NIF using figment's plugin. The resulting NIF can't really be used as is in Skyrim and need some more refinement (especially if wind animation is desidered) due to being currently unable to select BSTree/BSLeaf
Which version of Speedtree are you looking for?
I need "Speedtree CAD 4.2" I have the newest version but it doesn't support the .spt format anymore.