Definitely check all attachments for snug. Steering box, idler arm, steering arms, u-bolts, wheel bearing play, lug nuts, shackle bolts, etc. Proper inflation, balancing, toe and good spring bushings.
Then cut and turn your knuckles.
Or shim the springs.
Same thing happens to my '85 with Marlin's 4" springs up front, spring hanger and crossover. The aftermarket leafs move the axle forward and now the spring pad on the axle , following the arch of the spring, is tipping back a few degrees. This throws the caster out. A shim will correct it. I believe that is why some guys will cut and rotate the knuckles to correct negative caster created by modifying the suspension. I have run a shim to correct this. That creates another problem. Shimming the spring pad from the front, rotating the housing a few degrees, causes the crossover steering tie rod to come in contact with the top of the leaf spring. Also reduces the thread available for the u-bolt nuts.
I'm running a 6 degree shim now and plan to reduce to 4 degrees. I think that will give me clearance at the tie rod and correct the caster.
