I have a Lasco shower unit. I'm installing it in the basement on concrete. I have a 2 inch PVC pipe extending out of the floor. How much pipe do I leave above the floor? Most of all is if I buy a Oatley connector, after I secure it to the shower itself, do I just slip the shower unit over the drain without any type of tightening? There will be no room under the unit to do any tightening. Home Depot customer service looked at the brass Oatley drain connector and told me it just looks like you just slip the entire unit over the drain pipe and it shouldn't leak. Nothing to tighten around the drain pipe? Your help will be greatly appreciated.

Scott