I am unsure what you mean by a “small plate behind the booster”.
The only full VIN number stamped into the actual body of a Pantera is located on the top of the pedal box. It is not a plate, it is stamped/embossed into the actual chassis metal.
there is an aluminum plate pop riveted above the VIN that has a cut out section leaving the stamped VIN visible.
“3000 etc” tag …… I have been in the deTomaso family for over 20 years and I have absolutely zero knowledge or idea of what this is referencing
Have you used the search function on this forum? There is a wealth of previously posted information that will be of help for you in your search.
Larry