[Godey]

Under

Код:

dcmd_work(playerid, params[])

Put

Код:

if( GetVehicleModel( GetVehicleTrailer( vehicleid ) ) ==584) 
{ 
    return SendClientMessage( playerid, -1, "Haul Fuel from [LS]Los Santos to [SF]San Fierro with Petrol Trailer!" ); 
}
else if( GetVehicleModel( GetVehicleTrailer( vehicleid ) ) ==435) 
{ 
    return SendClientMessage( playerid, -1, " Haul Drills from [SF]San Fierro to [LS]Los Santos with Cargo Trailer" ); 
}
else
{ 
    return SendClientMessage( playerid, -1, "You Don't have a Trailer!" ); 
}

You can make more trailer types with else if!
Use https://sampwiki.blast.hk/wiki/Vehicles:Trailers