I'm not sure that thread was really conclusive... : (
For giggles, I tried something different, looking up the group suffix (3047A) across different prefixes (model) as a *part* number always gives me the same part, namely, front suspension upper control arm bushing kit.
The T prefix makes it a tool, so my guess is it's the tool for installing those parts, just don't have the secret decoder to tell which vehicle 58P is....
(Looking at this again, the 58 probably refers to 1958, but not as a model year, rather the first year the part that tool was made for will fit, P is probably the vender code for Motorcraft/Autolite (the part the tool fits).
The tool doesn't show up in the current available tools list, so the only way to know for sure is fgoing to be to find it in a repair manual for whatever it will fit ...
