OK, so I bought the spring perches from DIY (ordered anyway, should have 'em soon). Now, I have a vibration in the driveline ever since I did the 4 inch springs out back. I plan to change the pinion angle when I put this 14bolt under the Blazer and try to remedy the vibe. Without having to put the perches and the axle under the truck and trying to figure out a good angle, is there a formula or other way to guesstimate placement of these perches? I have help with a welder, but I'd like to be able to throw the axle in the back of my Ranger and just take it over to the guy instead of having to to the whole dang swap it his place. Ideas? Suggestions? I was thinking of just moving the perches forward about 1/4 inch on the tube and going from there. If it's too much or not enough, I can shim it. Whaddaya think?