Changes to wheel hubs

[Bob Phillips]

So in other words, the early vs late style front drums and caps are matched due to the different bolt size holding the caps on. If you wanted to change a truck from early to late style hubs ( or vice versa) you would need to change the drums and the caps together as a set. I do seem to recall (as per Grants comment) the the wheel studs on the back of a late model truck ( with flange) are longer to accommodate the extra width of the flange.