I have an ole '92 with a SM and mine too was cracked and leaking. Dryed out and I had some fiberglass repair stuff in the storage. It's that green stuff with fibers in it, kinda like bondo. My plan was to use some West System 3 Epoxy and a lil cloth, but times got busy and I wanted to get her going. That was two seasons ago now and still not leaking.
Plans are to pull it and sand down the poo poo puddy next winter and system 3 it properly but it's holding now...
