is it the V4 or V+ ? they changed the design on the V+ with no more cooling block. I have had both and on the V4 the block goes under the plenum, held by 2 screws, near the throttle body, basically under the plenum. When I took mine off, one screw had gone missing, but the problem is that you can't tighten them too much otherwise they crack the plenum... best design is the latest V+, tbh. The block comes with the plenum
Also, with it being second hand, are you sure the cork seal is still ok, have you had it re-sealed by Kinetix?