F-15N Sea Eagle/Seagle:
In the early 1970s, McDonnell Douglas also produced concepts for a carrier-based version of the Eagle designated the "F-15N", or more casually the "Seagle", with arresting hook and heavy landing gear for carrier landings. Some F-15N concepts featured carriage of the US Navy Hughes AIM-54 Phoenix AAM. The admirals, prodded by Congress, looked over the F-15N schemes politely, but the Navy was working on fielding the Grumman F-14 Tomcat as their BVR interceptor at the time, and there was never really much chance for the F-15N unless the Tomcat program collapsed entirely.
This drawing is based on the scale model below:
EDIT: Possible configuration of the 'actual' never-built Sea Eagle, based on the F-15A/B/C/D and fitted with reinforced landing gear, F-14-style IRST and FAST packs: