It's a pretty easy job, can be done with basic hand tools, a jack and jack stand(s). Only parts needed will be a pair of tapered alignment shims the width of your springs. Read thru the steps below to be sure you have all the tools you'll need at hand
1. Put truck in gear or park if auto. Set emergency brake, block rear wheels.loosen but don't remove front wheel lug nuts with a lug wrench.
2. Jack up front of truck under frame behind wheel until the tire clears the ground. Place jack stand under frame near the front. Lower jack until frame is resting on jack stand, checking that the wheel is still off the ground. (be sure jack stand is level and on a solid surface like pavement or a short piece of 2x12 if on grass or gravel, your life could depend on it!)
3. Remove lug nuts and wheel to gain access to spring and axle. (I like to lay the wheel on the ground under the frame just behind the jack for extra safety measure. Laying it under the axle would be another good place for it, making sure it won't be in the way of the next steps)
4. There are 2 U bolts securing the axle to the spring. With a proper size box wrench or 1/2" drive socket on a ratchet or breaker bar (this is NOT the place to try to use an open end, adjustable wrench or pliers! LOL!) loosen the 4 nuts as far as you can but do not remove them. Be careful that no part of your body is between the axle and/or brake drum in case the axle falls! The axle should drop down some. If it did not, pry it down with a large screw driver or pry bar between axle and spring. If you look in the space you should see the rounded head of the spring centerbolt and a depression in the axle spring pad for it to fit into. Hopefully there should be enough roon between the centerbolt and axle to allow the shim to be slipped on place between the spring and axle. If there is, slip a shim in place oriented to tip the top of the axle back more i.e. with the thicker part towards the rear of the truck. Place the shim so that the hole in the shim is under the centerbolt and over the depression in the axle.
5. Make sure everything remains in alignment and tighten the 4 U bolt nuts, be sure the centerbolt goes into the depression in the axle. This is critical because it is what keeps the axle from being able to slide front to back. If the centerbolt head is too short to go thru the shim and still protrude about 5/16" into the axle, you will need to change the centerbolts to ones with longer heads before using the shims.
6. If loosening the U bolt nuts does not allow the axle to drop down far enough to insert the shim, place another jack or sturdy support under the axle so it is about an inch below the axle. Carefully remove the 4 U bolt nuts and allow the axle to drop down to the support. Be careful, it is heavy! Insert the shim as above while raising the axle back into place. Replace and tighten the U bolt nuts. Remove the support to use on the other side.
7. Replace the wheel and tighten the lug nuts.
8. Repeat steps 1-7 on the other side, Be sure you insert the shim with the thickest part towards the rear of the truck.
9. After both shims are in and everything is tight (recheck that the U bolt nuts are still tight with the truck weight back on the axle) unblock the rear wheel and take your truck for a ride. It should require a slight more effort to start turning the wheels, but they should self return to straight after a turn more, and track straighter with less corrections going down the road.

 

Ax, thank you very much for taking the time preparing this outstanding set of procedures. The thought of working around these springs are nerve racking and this takes some of the fear out of it.

 

Make sure you use steel shims, not aluminum.

 

It's not really dangerous unless you unscrew the U bolts all the way and the axle falls on your fingers or the brake drum falls on your foot. The springs are quite safe to work with until you start to disassemble them by taking the centerbolt out, and even that is pretty safe if you do it right. (I just looked at mine and there should be plenty of thread to put in a shim by just loosening them.) If you are going to change the pins and bushings you may want to do it all at the same time and take the springs out one side at a time, disassemble the stack, remove every other leaf and put in the plastic slider strips between the remaining leafs. that will soften the ride considerably and lower the truck about 1 1/2" all around. There are instructions in the Mid Fifty catalog on which leafs to take out. Ask again or do an advanced search on spring disassemble or spring center pin removal and my user name for instructions on dealing with taking the springs apart safely. It's not difficult to do.