leaf springs bolts

[1973cuda]

Hi need some help on a 73 cuda rear leaf spring bolts. My question is the front mounting brackets where the spring eye is a 5/8 bolt x 4'' long does this have to be a harden bolt if so what grade of hardness. Then there are 4 smaller 3/8 bolts that hold this bracket to the frame should they be harded also thanks 4 any help.

 

[burdar]

You can still buy the correct bolts brand new. I'd rather have a stronger fastener then I need.

 

[Chryco Psycho]

the eye bolts are grade 8 , coat them with anti sieze so they do not freeze in the bushing , the 3/8 bolts were originally studs pressed into the mount but you can use a grade 8 bolt there as well .