Very interesting! I looked through all 3 manuals for it but there seems to be no recognition of it anywhere, not even in the electrical system diagram.
All I managed to find was this image, but don't that look like an hour meter??
Then I found this dash for sale, but that 2nd hole looks like a PO mod spot for an ammeter. You can still see the corner of the IH logo that woulda been there
Guess it isn't a very common feature
__________________
'70 107 with k301 engine swap
'71 106 with 38" deck
'70 147
R with factory replacement k321, 42" deck
'61 Original with 38" timed deck
'63 70 "pinkie"
1863 with 54" deck
'46 Farmall H, '50 Farmall Cub
105 x2 (parts)