I finally got my 7 cyl Sanden working in my 300D. The vent temp is 40 degrees:
The ambient temp is around 100 degrees (in the shade):
I borrowed the IR temp gun at my local radiator shop when I took the photo of 31 degree vent temp (first post), and just realized that it must be taking into account wind chill. I tried it on my 7 cyl Sanden in the 300D, and it read 17 degrees. I will take a photo in the 240 vent with the same thermometer I used in the 300D, and compare.