I'm driving a newer Freightliner now. Has a DD15 engine. And whatever auto trans. I have to say it backs beautifully. Nothing like that 579. I have to say, because of the electronics. It is a little higher quality than the 579. The 579 had super cheap electronics everywhere. It still ain't no Volvo. Am very happy with it.
The cabs must have some give in them if the rubber seals are leaking. I have never had one leak unless the seal itself was bad from changing them too much. I had to change the seal in my international after a lot of windshield changes, and the one in my KW was wore through the last time I had to change a windshield, there was not one available here, so I went ahead and used the old one, but it did leak, so I bought a new one, but didn't get around to changing it before I wrecked it. lol