So I got as far as finding the older version of SPT 3.10.5.
Then I realized, like the user above me said, that I must also downgrade my live EFT copy...
Good luck finding a patcher for that and please do update this post if you find one, as I had no success.
Technically, you would have to find someone with already patched files. ie. a working 3.10.5 install. Same thing is done when backing up an install and wiping your PC so you can keep your SPT version and playthrough.