[Shop-talk] Can someone identify this tool?

[Jim Franklin]

My dad was a diesel mechanic and now I have quite a few tools I can't
identify. One is this Mac CF-48  that looks like the business end was replaced
with different jaws at some point, judging by the weld quality.

http://www.groupwbench.org/Tools/tool_4.JPG

Anyone recognize it? We've been having a fun game of "name that tool" on
another this but this one has us stumped.