May have to be patient, very very patient
I bought a set of none OEM transom brackets for my 14ft Larson. I bought both, so even though they arent the original style, they'd at least be the same.
Over a 1.5yr later, an original style bracket, same side I needed, showed up on ebay. I bought it, have yet to install it.
Depending on where you live, you might try some metal fab shops. A few have been able to provide 1 bracket and had the other made up of 1/4in AL and welded. Again, I'd get a set made so they're the same. Welded new ones vs cast old is a pretty good replica....
IMO, no 'value' added by using OEM, I bought the 1 because it wasnt expensive, and my replacement set are completely the wrong style bracket for an early 60s Larson. They're extremely angled and faceted. Original was rounded w subtle curves. For sure dont run your Tracker w out the corner bracket. My Larson had a dairly large crack forming in the transom/hull corner, immediately adjacent to the double riveted seam, so hard to fix, from the bracket missing.