Question after removing overload springs

[68shortbedinmo]

I have done a half hanger flip and removed the overload spring. Now when I put my truck in forward gear and give it gas the front of the rear end tilts up and if I put in in reverse it tilts down. Is this normal with the overload spring removed ? Or is it something I need to look into ? Do I need to put it back ?Or is it a completely different issue ? Is my drive shaft too long now ?

Thanks