High and Low side a/c

I have used the tool loaner program for a vacuum pump and hose manifold for checcking my a/c. The engine (340) in it is not the correct engine so I'm trying to locate the high and low side to hook this up. I took 2 pics of 1) my motor 2) the compressor witch has a fitting on each side of the picture right in the middle. The reading I've done suggested they would be of differing size but they seem the same. It could be from being R12 fittings instead of R134a...I'm not sure, but i would guess the one of the left would be high side. Any help? lol
engine340a.jpg 20200818_135313.jpg