Question about my StepSide Bed?

[arkracing]

How do I tell if I have a 67-72 step bed or a 73-87 step bed.

I'm a little scared because I was just on Mar-K's web site and they said that the bolts on the angle strips (the ones spot welded to the bed side) were welded the the strips on 73+ beds.

I thought my bed was a 67-72 but i just ground all the bolts off my angle strips cause they were welded onto them.

were these bolts also welded to the angle strips on the 67-72 step beds or did i get screwed over when I bought this bed????