It can be welded ,check out muggy welding rod on Amazon. or you can braze it and hope for the best, Also you can weld with special rod for cast iron heat cast weld, peen weld, bury in sand until cool. All the above will work. I would use muggy weld it is by far easy.
Also try here lot of GMC guys
https://oldgmctrucks.infopop.cc/eve?s=272004236&csra=Y