Are you using the proper length bolts?
The factory bolts are 1 3/4 inch in length.
Rather hard to find them in that length at hardware stores, other than in 1/2 inch increments such as 1 inch, 1 1/2 inch, 2inch.
Im using what came out of the car when I tore it apart. If someone else may have swapped them prior to me owning it I dont know. I have about 3 threads showing past the nut. My guess is they are close to the 1-3/4 length. I will take a measurement when I tear it apart and I will get back to you.
