Bah, I meant radar altimeter. I was thinking about GPWS. Though practically speaking, there's little functional difference, and not enough to invalidate the point I was making.
http://server.3rd-wing.net/public/Manuels%20DCS/DCS%20FC3%20Flight%20Manual%20EN.pdf
Pg 93, ILSN mode for F-15C:
"At an altitude of less than 1,000 feet, along the right side of the HUD, there appears a radar altimeter scale, graduated in hundreds of feet. The current radar altimeter bar moves along the left side of this scale."
If you were trying to correct me, you could've pointed that out yourself.
The question still remains, why would ED remove these messages from the F-15C?