Zinc pessimist? Not really. And I agree: Not every casting has it. However, looking at the OP's picture, The manner of the breaks with the tabs remaining, and the bowing of the remaining side frame are classic signs of ZP. If you look at the center hump on the side frame of the other truck, you will note the rough edge along the backside. Again, a classic symptom of ZP. I see no sign of ZP on the remaining frame, at least in that picture. Given the variable nature of ZP, especially when it strikes and how it manifests itself, I'd start looking for 4 new frames or a means to replicate them using the one remaining good frame as a template. Unfortunately, I no longer have access to an XRF. Otherwise, I'd say send the parts to me and I could tell the OP how much lead contaimination is present.
Chris
LVHR
