I checked the manual this morning and the overall width of the 48-52 front drum is supposed to be 3-15/32" and the diameter of the center hole is shown as 2-7/8". On the 53 and later front drums, the width is listed as 3-3/64". Rear drums for 48-52 show a width of 2-25/32". Hope this helps. - Bob

 

I ran across this truck on the Ford Barn and it shows what I'm betting is the type of drum you were describing in the OP? This is on a '41 1/2-ton.