That guy on the gif looks annoyed so I thought of sarcasm for something. Glad that it's not like that.
Dug a bit further and found the case. Each time game creates txd.img it results different *txd files inside this *img archive. Content of these files stays the same but technically they're different (so you can't compare them by checksum/MD5). Luckily we have Magic.TXD which could unpack txd files and unlike R* method creates each time exactly the same txd files from the same content. So I unpacked all resources of all txd-s, packed them back and compared resulted files by hash (*md5-files from HashCheck, ExamDiff for comparing them and creating the list + txt editor with regex support for removing unnecessary symbols on the left).
Here's the list of modded files:
Theoretically textures were replaced with HD ones so *txd file sizes should be different. Well, they're for most of the files but 3 of them remained the same (dam, dambase & pumphouse).
So almost same as before:
* Get original txd.img
* Extract files from both (original and modded) txd.img archives into some separate folders (e.g. txd-img, txd-img-mod)
* Open WinMergeU.exe. <Edit> -> "Options" -> "Compare" - "Folder". Change "Compare method" to "Size"
Then go to File -> Open. For the "Left" choose "txd-img" folder and for the "Right" respectively "txd-img-mod". Click OK.
* "View" - uncheck "Show Identical Items"
* Select all files (Ctrl+A/ Edit -> Select All), right-click somewhere on the selected area and choose "Copy -> Right to..."
* Congratulations, you have almost each modded file in the separate folder. Now just move there the rest of them (dam.txd, dambase.txd & pumphouse.txd).
Well, that wasn't boring also found some useful utilities...
And yeah, you're welcome