[Not available]

Oh. Didn't even consider it being models and not IDs. This should be the best solution then:

pawn Код:

public OnPlayerEnterCheckpoint(playerid)
{
    new
        truckid = GetPlayerVehicleID(playerid)
    ;
    if(GetVehicleModel(truckid) == 403 || GetVehicleModel(truckid) == 514 || GetVehicleModel(truckid) == 515 && IsTrailerAttachedToVehicle(truckid))
    {
        SendClientMessage(playerid, 0x33AA33AA, "Thank you! Here's $1.700!");
        GivePlayerMoney(playerid, 1700);
        DisablePlayerCheckpoint(playerid);
        return 1;
    }
    else SendClientMessage(playerid, 0xAA3333AA, "Hey! Where's your truck?");
    return 1;
}