Originally Posted by
fryboy
sad to say it depends , some of the earliest model 45's used the same pitch of threads as the #1 sizer ( i call these "informally" generation 1 45's ) most have the newer pressure screw pitched threads , no way to honestly tell from here ,hints are newer 45's have a aluminum reservoir cap , a pin ( with cotter keys ) handle pivot ( as opposed to a shouldered bolt ) a spoked cast iron wheel type cap was carried over from the #1
if you have a 450 and your two piece pressure nut fits the thread you're good to go , of note the pressure screws arent too expensive but there is a wee bit of difference on the top shaft ( a lil longer and a thicker shaft at the top that will require modding the cap by drilling the hole larger , 5/16" iirc and easy enough to do ) also of note i have an original #1 with the square drive screw ...some report that the threads arent the same yet i can ( and have ) used a newer o-ring pressure nut ( fit right on ermm i mean screwed right on in just fine [shrugz] ) so chances are good that you do not need a new screw