It's for my 76 f-100. How much lift does this give? Any problems with pinion angle? Thanks.

I'm assuming that you mean "shackle flip" where you flip the shackle over so it is in compression instead of tension. Theoretically, you should get a maximum of 4" of lift from doing this because your shackle is about 4" long and if it is still mounting to the frame at the same location, the rear spring eye drops by about 8". Seeing as how the axle is about halfway between the rear spring eye and the front spring eye, you get about half that 8" in lift. However, when I did this to my EB, I layed the shackles over at about a 45 degree angle which decreases the amount of lift in two ways. First is the obvious where the shackle is not pointing straight down. You lose about 3/4" because of this. Second is something that is rarely mentioned which is the fact that, at a 45* angle, the shackle has a spreading affect on the spring. My springs (an old set of 10 leaf Nationals) had an inch of so of arch to them before the shackle flip. After the flip, they were completely flat. This all worked to my advantage because I didn't want too much lift in the back. Of course this spreading affect will be different depending on the stiffness of your springs. My pinion angle needed to be dropped a bunch following the flip (maybe about 5 to 7 degrees).

Tom

thanks, that is what I needed to know

When you flipped your shackle did you use a trac bar in the rear, or did you see no reason? Ive heard of people saying you need one. Also did you replace your shackle bushings when you had it apart or the stock ones probably adequate as long as theyre not to badly worn.

I did not have to run a rear trac bar but I did use new poly bushings in both the spring eye and the shackle eye. The shackles were stock length. Handling was a little on the oversteer side but, other than that, it worked VERY well.

Tom

P.S. Sorry about taking so long to respond.