RK, Had the exact same problem on my '58 Apache and was broken when I got the truck. And rather than a crack on the mount that was intact it had already been welded some time before I acquired when I got the beast (no idea how long it had been that way but it evidently held for some time). Guessing they both were not welded because the shock and portion of one mount was lost when the damage was done.
Experienced the same thing you did when trying to find something new - nothing that is correct. I watched eBay for several months and got lucky finding two NOS mounts for a very good price (too long ago to remember but under $20 for both). Ground the rivets off and plan on attaching with bolts when I finally get around to putting shocks on. I'd guess someone really hit a dip/curb/pothole really hard to compress the shocks completely and transfer additional forces on the shock mounts.
