What's engine does this GT40 have ?

I just saw a video of a gt40, mk1 I guess, and i just love the sound of it, and I want to know what engine does it have ?

Here is the video on YouTube :

MK1, Small Block, could be any Cubic inch in todays world, 5 speed shifter gate therfore ZF,, MK2 T44 would only have 4.