I just discovered that Devcon and Marine Tex are made by the same company, ITW Performance Polymers. The Devcon line includes a bunch of different products as well as epoxy putty. They advertise it for machine repairs like you did on the backhoe. That would generally be with a steel-filled epoxy.
They recommend Marine-Tex for fiberglass repairs (I've used it on my fiberglass boat and can report that it works well.) Here's the blurb from their website: "Marine-Tex is the legendary high-strength repair compound designed for filling, bonding and rebuilding wood, fiberglass, ceramic, glass, metal, masonry and many plastics."
My guess would be that a Devcon steel-filled epoxy would be just as good for a block repair as Marine-Tex. [on edit]This might be a concern on a block crack repair. From the Devcon Plastic Steel TDS: Temperature Resistance Wet: 120°F (49°C); Dry: 250°F (121°C). ITW doesn't report temperature resistance for Marine Tex.

Last edited by klhansen; 11/13/2024 8:44 PM. Reason: added more info
Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.