Dipstick tube hitting??

nm9stheham said
Just a word of caution: There have been a few cases reported here (including pix) of the dipstick getting caught by the crank and a piece broken off and wrapped up in the crank.

That was a real common slant 6 problem. Sometimes you need to put a slight bow or bend in the dipstick tube to make the dipstick clear obstructions.