I suggest that you start by trying to find a saw repair place in your area. Sears didn’t actually make the saws they sold and the same saws, or very similar, were also sold under other names. Most old saw repair shops have a grumpy old guy in the back that can take a look at your old part and tell you what else it was used on.
If he points you in the right direction, having him sharpen all your blades or bringing donuts the next time you go there is a good idea.
Henry in MI