Sway bar mounting Bolts

I have a 1963 Econoline van '89A'.
I purchased a Sway bar, straight.



I Know  that the bolts to attach the 'U' bracket to the chassis is 3/8" fine thread.

My question is what length and grade bolt is correct?

I added a sway bar last year on my 67 PU. It already had holes in the frame for the bolts, Don't know if a 63 has them. Due to the U bracket about any bolt would work about 1" (25mm) long, I would use a Grade 5. Good luck with the shock bolt removal. The ride is better.

The anti-sway bar was optional on all 1961-1967 Econolines, so the holes in the frame are on all of them.

I agree with the 1" and grade 5. It is OK to be longer, since the end of the bolt will be inside the frame.