Quick little ReShade tip:
If you need to find a previous version of ReShade, for those from the last couple of large revisions (so 5.x and 6.x, I'm not sure if it works for earlier versions) you can just copy the download link for the most recent one and change the version number in the url.
So, the dl link on the front page of the ReShade website is currently for version 6.1.1, and the url for the addon version is https://reshade.me/downloads/ReShade_Setup_6.1.1_Addon.exe
You can manually change that link to get another version. For example, if I wanted 6.0.1 I would change the link to https://reshade.me/downloads/ReShade_Setup_6.0.1_Addon.exe
Someone also keeps an up-to-date repository on mediafire of all old versions going back years. This is linked to via the official ReShade forum, but it's up to you whether you want to take the risk downloading something from mediafire or not.
Remember, for both of these methods you will only be downloading the ReShade binary, not any of the shaders. When installing ReShade you'll be prompted to download shaders as usual, but they won't be shaders from old versions, they'll be the most recent shaders. If you've decided to use a particularly old version of ReShade you may run into problems. Try to stick to the most up-to-date version of ReShade that you can.
For an explanation of the difference between the ReShade binary, shaders, and presets you can take a look at my Understanding ReShade guide.
