Hello, I recently deleted my heater and AC, so I took the little 3/4 plugs they have in the help section and clamped them on to the radiator outlet. Well they work great but what I have noticed is that they will crack at the edge(see picture). Has anybody had this problem or know of any different way to plug the outlet on the radiator.

This pictured capped connection should not be capped. This part of the normal path of the recirc from the block. If you don't run the heater core, connect the hose going to it here.

I should have said the hose going to the heater control valve instead of the heater.

I've had the same problem but I didn't delete my heater, I just made it old school. The heater supply hot line comes from the intake manifold and the return from the core goes into the top of the waterpump. This type of setup allows for coolant to move through the block reducing hot pockets.
A solution to your cracking plugs is to use a rubber hose with a wide (or 2) hose clamps and an aluminum terminal aka button cap.
You could run a line from the intake manifold to that fittings just to be certain there is coolant flowing even on a cold block.