None of the today's new replacement pumps are going to look exactly like the original.
It's not economically practical for a large business to rebuild a pump that may have billions X billions X billions of operating cycles.
It costs too much to fix a part that's just completely worn out.
I happy to have a pump that fits well, installs well, pumps out between 3 an 4 PSI and lasts a long time.

If it is an original AC or Carter, there's usually a number stamped on the base, have a tag or a cast part number somewhere.
This is what you need to do research on for on a 100% original truck (trailer queen).
Join AACA and post your question.

If you can't stand the look of a new replacement pump, spray paint it flat black so nobody can see it.

BTW, Spectra is a great Canadian company especial fuel tanks. I looked up the Spectra Premium SP1124 that Tiny mentioned.
The website says 5 to 8 psi. It okay from a quick few seconds of priming but if you plan to use it all the time, then you need add a pressure regulator.

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."