[hugger6933]

Don't flame me for this but what about the o-ring around the filter. Now this is where the flame part comes in I don't remember the 400 trans and how the filter goes on. Whether it is a bolt on or push in filter like the 700r4. The o-ring could be cut [or left off] and that will cause just what your describing. I also remember one of those bolting on with a gasket under the filter and that will cause the same problem. Also the deep pans normally come with a adapter to drop the filter down into the pan So to make up the difference in the deep pan as opposed to the regular one. But the deep pan takes about 2[two] more quarts than the regular the thinking is more fluid will cool more area.[also the aluminum helps in that]But I'm sure you already knew that, sorry for my rambling