There were several tank switching systems and pumps used depending on engine size, EFI or carb etc.
On my EFI 5.0, I replaced the troublesome non electric switch / reservoir system with an aftermarket electric switching valve.
Here is a photo:
You may have had a similar electric pump, probably the 3 port version for a carb engine. EFI uses the 6 port version.
Can you get a photo of the connector etc?