45 “ jugs

[46CHF]

Can 45 jugs with 3/8 studs for iron heads be modified to accept aluminum heads

[kitabel]

The stud thread (3/8-16NC) has the same pitch as the bolt thread (7/16-16NS), so drill to 3/8" (pilot) and re-tap. Note: the 7/16-16NS is not coarse or fine but special, use the right tap. It's the same as VL, UL, knucklehead - but not K/KH, or big twin OHV.
Alternative: make small sleeves to reduce the hole IDs in the heads, but you still need longer studs and something to replace the heavy cone washers under the nuts.