The perkins 6.354 engines use a fueled staring aid rather than a glow plug setup, not all have them installed and I've only seen a couple T6.3544 versions in person but neither had this option installed, but that is must be where it would have been installed. With the aftercooler tube stack built into the combined intake and exhaust manifold, it would be the only place to install one.
The 6.354's seem to start very quickly and even well in all but extreme cold weather without any starting assistance so kind of doubt it is necessary.