This may or may not answer your questions on were to install your probe for the EGT, but I hope this helps?
When the 6. 7L engine was first introduce these question surfaced. TDR ran an article in issue 61, which is AUG/Sept/Oct, 2008 on how to install and were to install the gages with the probes that are required.
You can access the article on line at the TDR home page. The article starts on page 36. I hope this helps?
Jim