Remove the socket head plug located next to the oil dipstick knob and observe the level on the dipstick attached to the plug. If necessary add transmission oil thru that same hole.
20- 24 ounces
Tis underneath the transmission on the left front of the square oil tank.
1999 Harley Davidson fuel line diagram
Harley-Davidson Race Across America - 1999 VG is rated/received certificates of: USA:E
According to Harley-Davidson, a 1999 Fat Boy gets 56 mpg on the highway and 43 mpg in the city. Your mileage may vary.
carburated
58 hp
Three
you need to take title or registration to a Harley dealer so they can order one
The motor oil drain plug is located on the underside of the transmission, closest to the right side of the bike. The one closest to the left side is the transmission drain plug.
80/90 semisynthetic hypoid gear oil is what the factory put in it but I use Red Line Heavy ShockProof fully synthetic gear oil. Not cheap but neither was your Harley.
Most likely it is a harley Davidson part # 66010-97A