"The 'F' rod diameters didn't change,"
Not.
http://i105.photobucket.com/albums/m...945%20Pg.4.jpg
ZA 0894 No.1 49.5" long 3/8-3/8 diameter both ends male/female
ZA 0895 No.2 49.5" long 3/8-1/4 diameter at ends male/female
ZA 0896 No.3 49.5" long 1/4-1/8 diameter at ends male/female
I've also seen a 'battle' aerial 4'+- 3/8(1/4??) male base 1" 1/2 long with balance 1/8 rod 3/16 ball on top.
There are probably other variations around.
Actually that is why a WS38 has 2 or 3 adjustable holes to insert aerial rods.
Geoff