opencart 1.5.1.3 installation files [clean]

Hi there,

i need to update an opencart shop which still runs on 1.5.1.3.
It was not updated before because there were many changes in core files which would crash the shop on update.
i've just started moving from 1.5.1.3 to 1.5.6.4 to continue from there to 2.x. but it's almost impossible to prevent losing custom functionalities.
i need a clean 1.5.1.3 to diff it with the shop files to spot all differences.
can anybody provide clean files? The download link in the official archive is broken.

best regards,
simon kraus