The following psbplus.src options are relevant for Starship Parts:
TransportComp (Yes/No; default: Yes)
Enable the component transport feature.
Note that if this feature is disabled in mid-game, the "unload" friendly codes can still be used to empty possible remaining transports.
FreighterCarryOnly (Yes/No; default: Yes)
If enabled, only freighters can carry parts. A freighter is any ship that has no weapon.
If a ship becomes ineligible (e.g. by being refitted), it can no longer load parts, but can still unload parts it is possibly carrying.
NonCloakerCarryOnly (Yes/No; default: Yes)
If enabled, only ships that cannot cloak can carry parts.
If a ship becomes ineligible (e.g. by leveling up), it can no longer load parts, but can still unload parts it is possibly carrying.
CargoSpacePerComp (number; default: 40)
The minimum cargo space allocated for each part aboard a ship.
TagSpecialTransport (Yes/No; default: Yes)
If enabled, ships that carry parts will receive a "ST:" prefix for their ship name.
Unless ship names are filtered at the host side (pconfig.src AllowShipNames=No), that prefix will be visible to all players.