Subframe connectors for a driver/cruiser, necessary to weld to floor?

Darter6 said
View attachment 1715841264
Mancini connectors. Installed about 20 years ago. Works for me.
They were bolt in style but were welded in.

X2 for making a set yourself from 2x2 that look like this. I run 10.30's on a homemade 2x2 set that look exactly like this, NOT tied to the floor.