According to the Fram application guide at http://www.power-21.com/honeywellpower21i/fram.aspx
it's the PH8172.
Kohler 1205001 crosses to STP 3512.
Baldwin - B10140 Fram - PH8172 Kohler - 1205001 B&S - 492932
Fram makes a poor quality filter which I advise you to not buy. Purolator on the other hand makes an excellent high quality filter which costs no more than a Fram. Your Kohler filter 1205001 cross references to a Purolator L35310 sold at Advance Auto Parts and some Walmart stores. I recommend you use only synthetic oil in any air cooled engine.
Fram PH10960
12-050-01 may be a better number to search oil filter suppliers for a substitute. The Kohler oil filter 12-050-01 was superceeded to 12 050 01-S1. Fram still has the old number and it crosses to Fram filter PH8172
KOHLER 1205001
PH4967. Fram specifically says the Kohler 7.3E uses this filter
Fram PH 8172
ph7575
sfwe
PH3614
You can cross reference Kohler Air Filter 233116 to Fram. Kohler is a quality OEM filter. There are cheaper alternatives, but Kohler is top of the line.