In my experience without the adapter plate the fan is too low. A shroud helped but after switching to the higher mounted water pump using the plate the cooling ability of the system was much better as the truck could idle in hot weather and not warm up like before. I believe the left hole for the adapter plate intersects the bottom of a head bolt hole and not into the jacket if drilled a bit deep. That mod is a no brainer due to the reasons Dave mentioned and hat’s off to the inventor of that one.

Without the adapter plate here's where the fan sits:

http://rides.webshots.com/photo/1377765981023244788uDinRU

1952 1300 Canadian 1/2 ton restomod
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