: two questions on the tub install. I'm doing a alcove install on a cement slab. Should I still put mortor under the tub, and second the tub seems pretty steady just sitting alone in the garage, do I need to put hoizontal supports under the lips of the tub??

Jason,
Most use a horizontal support on the back wall.
With cast iron, there is no need for support under the tub.
It's more important to shim at the front apron to prevent rocking.
With the back support installed level,
the next step is to check the front apron to see if it meets the floor, if not it may need shimming.