Help!
This is my first time on here.
I need info on installation of a used maxx shower module that looks pristine but I am not sure how to get the three pieces, base, middle and cover sealed against any water leakage. It has a manufacture date of 1998.
It measures about 84"high, 37" deep and 65" long. It has a built in seat and two shower grab bars.
Where do I start?

Thanks.