Unfortunately, Golden has decided that this part will be no longer available and there is no substitution available.  If your brackets are broken, the best alternative would be to go to a local “mom and pop” weld shop in your area, take the other bracket off if it is not damaged and have them fabricate you another bracket.  If one bracket is bent and the other one looks OK, you may can take them off and “backyard engineer” a fix for the bent one, using the good one for a pattern.