I have three 50's Ford tractors, a 59 641, a 58 841, and a 55 860. At the very front of the transmission case on each side of all three there are three tapped 5/8 holes per side. The holes on both sides on my 860 are plugged with smooth plugs. In a forum post that I should have saved, there was a picture of that area of the tractor that someone posted that appeared to show the three holes plugged like mine are on my 860. Were these holes plugged when these tractors were new? Mine are very neat and are not broken off bolts.
Left side.
Right side.
Left side.
Right side.