Detail of the main fuel valve (left), main LOX valve, and lower LOX dome inlet on the upper left F-1 engine.
With the horizontal
weld on the side of the LOX dome inlet, this has the newer, "fish mouth"
style inlet (see my page on the lower left engine
LOX inlet for additional information).
I'm not certain whether the later engine mockups (Saturn
identifies this engine as FM-105) have the "fish mouth" LOX inlets, or whether
this is actually an early production engine.