Expedition Bi-Fuel conversion

My 2003 Expi came with the Triton 5.4 motor. This motor was also offered as a bi-fuel version, gasoline and compressed natural gas.
I can't seem to find what parts I need to convert mine to a bi-fuel
motor.
Any help would be appreciated
Thanks
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.