E4od's do not have the by-pass valve. It started on the 99 model that has the 4r100 IIRC
Here's a picture
http://www.dieselsite.com/index.asp?...ROD&ProdID=172
FWIW, I bought the Tru-Cool 4739 MAX from that site w/ the thermal by-pass and like it alot.
http://www.dieselsite.com/index.asp?...ROD&ProdID=205