What do you have to loose?
I welded a completly broken in two exhaust manifold for our john deer tractor with some of that nickel rod they sell at tractor supply for cast iron. I warmed the whole thing real good on the wood stove and with the torch, then welded it and left it on the stove to cool slow as the fire went out. The tractor vibrates a lot and it has been a few years now and it is still holding fine. The whole end that holds the muffler up out of the hood broke, so it is not like it is bolted to the engine and cracked again but still on there, if it crackes again the muffler falls off.
Give it a try....
Grigg

And i am not a profesional welder, I took a night class at work for a few nights a week for about two months, just enough to learn how to stick weld nicely.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-