Not sure what you mean by a mast erection pin. Chrysler used a cast aluminum square peg that had a little bend in it. The base of the mast had a rectangular slot which you placed over the peg and then you walked the mast up (with the side stays and backstay attached, of course). If you have a mast base that takes a pin, then it was changed from the original design and you have to give us more info as to what type of hinge arrangement you have. You can always get a bolt the right diameter and length (stainless is best) to get you buy. If you use a mild steel bolt, use it only temporarily until you get the SS bolt or pin. More info, please. Then I might be able to help.