b4 rear shock towers, 2 types, same part number ??

[rondoolaa]

i have 3 shock towers new in packet as spares for my b4,

all of the packets have the part number #9572 even though there are 2 different tower styles,

as my batteries are a little bigger i have to grind off 2mm from the standard 2mm gap on the bottom of the shock tower so my battery hold down plate goes under the tower,

one of the towers in the packets has about a 5mm gap at the bottom and doesnt need grinding down, and the upside down triangle shape just below the body

post is filled in on the one with the 5mm gap and not filled in on the ones that i have to grind down,

how come there a 2 different towers with the same part number ,

the tower on the left is the one i dont need to grind down,

the tower on the right is the one i need to grind down and have done already in the pic,

thanks for any info