How many bolts?

Hey,
I just took off my front and rear bumpers and I am going to build new bumpers. I have the general design for both bumpers mapped out. I am going to put two shackles on each bumper. How many bolts should I use to mount the bumpers and where should I put them? I don't think that the 3 per side on the front will be strong enough. Pictures would be great is people have them. Thanks in advance,
-Abu

http://www.rigidco.com/bumper_mounting_system.htm

This may help with the front bumper.

http://in.f1.pg.photos.yahoo.com/ph/jjvanden/detail?.dir=/public&.dnm=Dsc00462.jpg

there are 8 bolts on the rear + 5 bolts on each strap = 18 bolts

as many bolts as you can possibly fit!