1998 36 FDS kitchen plumbing drain

[gmcgene]

While searching for the kitchen plumbing Studer vent ( which I found high up under the counter at the rear/back of the slide) I found a 1 1/2" white flexible drain hose that connects the kitchen and shower black abs drains to the gray water tank. The white hose makes a 180* turn from the upstream connection to get down and around to the tank. That turn results in a kink at the upper connection.

There seems to be part of a bulkhead missing between the rear of the lower cabinet/slide and the area containing the holding tanks.

I understand that there has to be some opening to allow the hose to move along with the slide, but this opening seems excessive. It allows road grit up into the area where the plumbing connections are located. And the opening is large enough to allow small animals access into the lower sink base cabinet.

Is this a factory installed situation or has it been modified be a previous owner? Something seems to be missing.
I've never seen inside a coach slide before so I have nothing to compare to.

Thanks for your input.