When it came time for the seat belt installation, I had to fab up a h.d. 1/2 inch bolt bracket for the belt on the trans tunnel side. (I used the factory seat belt bolt hole on the door side)
The factory seat belts anchor to the seat. The 3 inch racing belts need to be alot better than that.
So I took a piece of 1/4 in. steel plate and bent it to the shape of the floor. Then I welded a 1/4 inch bolt to the plate to help hold the assembly to the floor.
The grade-8 1/2 inch bolt is captured by the welded tab on the backside. This prevents the 1/2 bolt from turning when I tighten down the nut. No welding on the grade 8 bolt means no loss of strength.
Here is a shot from under the car after installation:
