Tyco Electronics Superseal is the name given to the sealed connectors on our MGs. These are most often seen on the Lambda sensor, the fuel pump and the OBD port that is so useful for use with GuzziDiag and assoicated hardware/software.
The good news is, that these are available from the likes of Element14/Allied Electronics and RS Components. Prices are not obscene with a housing (3 way) coming in at less than $2 each (but you need to buy five...); pins and sockets to suit are also available.
You want to customise you steed these are the connectors to go to. Incidentally, these are part of the AMP stable, now owned by TE, and even more especial, is that they are designed in Italia! Simply can't go wrong...