endura

Hello. About once a year when my Endura is parked at the exact wrong angle during rain the front most floor of the cab over gets wet. Anyone with an Endura seen this? How do you remove the square piece at the front?

Heya folks! I just bought a GMC Endura 3500 cutaway with the plan of making it a mobile salon and a travel vehicle. I got it for a really great price, since it needs only about $500 worth of work to make it run well. But now I'm worried that there isn't enough space in it for what I want to do...