I'm not sure that the crack is the problem, but I attached a picture of a block to show what the crack looks like. It's not my block, but you can see where I drew the lines, that's where mine is cracked. The crack is only on the bottom face of the mounting pad and doesn't extend up the sides of the block. One thing I can't be sure of is if the crack flexes when starting.

I found a starter brace but I don't know how it bolts up to the block. If the crack needs to be welded then I can have that done, but it would be a lot easier to put the brace on. Thanks for any input.

 

that brace doesn't look like anything GM ever installed on any third gen, so you're on your own with that, but if you find an older GM starter brace and use it, it won't remedy the issue with the crack. Welding is a good option, but welding cast iron seldom turns out well. I've done it successfully, but I was reshaping intake ports in Vortec heads, not fixing any cracks.