From all the Mark IV combos that I have seen it seems that the cooling fan is mounted on near the bottom on the right side when looking at the rear of the amp.
Hey no problem. I actually found a close up on another auction but it just shows the little angle brackets that I am sure that you already have anyway. It goes just above the reverb tank where you can get it in there next to the speaker frame.
I am always trying to help where I can. I am glad that I was able to help you out. Good luck getting your fan mounted. Rock on \m/
Thats the same location for the Mk2's and Mk3's. The fan is fixed to the back panel and side panel with two small angle brackets. I found that you will need to remove the speaker to gain access to these fixings.
