Long time reader, first time poster here (haha). I decided to post this because I couldn't find any answers to my questions prior to going through the process. It was very frustrating, my back hurts, and I spent a lot of money in gas, so I am posting this to hopefully make things easier for you than it was for me. Unless you work on vehicles full time with access to a shop, go ahead and plan on taking your truck to a spring shop. Try this if you want to save a few bucks though.
1994 Z71 Chevrolet (half ton/heavy half/4x4) without a torsion lift, though my truck seems to sit relatively high. I currently have 265R16 tires on mine.
What I did:
Changed my leaf springs to a set with two additional leafs from a 3/4 ton (yes they fit half tons), purchased everything separately, changed my shocks, tried out some larger tires so I know what to buy next. The newer springs with more leafs/leaves changed the ride height to a perfect level.
Why I did it:
My truck was sagging, not a lot, but enough to where I noticed it. It was also sagging ever so slightly to one side, not much but enough to where I thought I was losing my mind. The ride was also rough even when I wasn't hauling anything. I noticed it when my buddy's truck had a much easier ride. I also noticed that my front suspension seemed to react "harder" than other trucks to bumps in the road.
Later I found that one of my main leafs was broken at the eyelet, the other side was broken at the U-bolts and I couldn't see it. I had probably been driving like that for maybe one year.
New parts and what I spent:
Used leaf springs from a junk yard (I opted for six-leaf springs from a 3/4 ton) : $200 for both (The junk yard will probably saw them off and hand them to you.)
New shackles x2 : $55
New U-bolts x 4: $35 (from a 2000's model, they fit as long as you measure them)
New things that the U-bolts attach to: $45 (again, from a newer model, the shop said they've worked in the past)
New bushings x2 : $40 (get the stock ones, trust me, all the others are a headache)
New shocks x4, replaced a few months earlier : $250ish (don't waste your money if you haul, get the good ones)
Had a shop handle the rest, yes it is much easier : $330 taxes and all
Used newer model rims with bald 305's from Craigslist : $75
*This is probably the cheapest route to follow give or take pricing on a few items.
*Ebay was used for Ubolts and shackles, use Ebay for the bushings too though.
Needed tools IF you remove the old bushings on your own:
Circular bit (1 5/8" I think, measure yours first) : $20
Power Drill and Sawsall: I already had one.
24" breaker bar : $15 on sale at Harbor Freight
*Don't bother with electric or battery impacts, they won't work.
*I'd just let the shop press them out when they put the old ones in and save a few bucks.
The best path if you aren't a full time mechanic:
Note first: I found that my ride stiffness didn't change much from the old springs (broken four leafs to the new six leafs). It is actually a bit better. My buddy also confirmed this thought when he did his, though he said his was a bit more stiff. How many leafs is your choice though.
1. Find a spring shop and get an idea of what they will charge to swap the new ones on (I was quoted $270). I explained that I already had everything and intended to do it myself but gave up, it wasn't the first time they had heard that. You could check what they would charge for shocks too, but those aren't hard to change. I'd have probably paid up to $65 for them to change the shocks to save an afternoon, up to you though.
2. Purchase/order everything needed first so it is on its way. Discuss what shocks to use with someone who is an expert, not just the guy behind the counter. The pricier ones are usually better though. If in doubt about something fitting, buy it from a store so it can be returned.
3. Purchase used six-leaf springs, make sure they aren't broken or cracked. Saw away the crap if needed so the old bushings can be easily pressed out by the spring shop. You could use the circular bit to drill down around the old bushing. Work it back and forth with the breaker bar until free. Turn it one direction with pressure on the other side until it twists out (it takes a while). OR just saw each side of the bolt off and let the shop press them out.
4. Don't waste time trying to have the bushings pressed in or out, it will likely be included in the price if the shop is putting them on.
5. Take the truck in, explain that you want to make sure it won't be sitting ass-up like a jackass, and them them do it. This will save you a back ache, lots of gas money, and many curse words. I kid you not, messing with old rusty bolts and bushings is a major pain in the butt, let them do it!
6. Change your shocks afterward to avoid wearing them out prior to the spring swap (if you didn't want the shop to).
My truck looks like it got a little bit of lift compared to the way it used to sit. The six-leafs fit perfectly without the truck sitting too high in the back. The stiffness didn't change all that much for me and the ride is a bit better. I recommend changing your shocks if your truck is old as sin like mine. I found that I could play my old shocks like an accordion. Hey, I inherited it so leave me alone! Keep in mind that changing your springs doesn't change the ability of the axles, so don't risk breaking them by overloading the truck.
I found that I could fit 305's on my truck stock, but since I haul and do some minor off-roading, I won't be going over 285's next time. I also read another post where a guy had six leafs installed in order to haul his camper. He changed his tires to 10-ply tires, which I will probably do eventually.
I took this path to avoid the markups on parts at the shop, and I honestly thought I could do it myself. Mistake. Skip the machine shops, get what you need, and have a spring shop do it. It will save you a few headaches, lots of sweat, time, back pains, and gas money.
Pictures are added below of the end result, still with 265R16 tires. The only concern I have moving forward is the dependability of my newer springs, but brand new ones were crazy expensive so I risked using used ones. Honestly, I'll probably miss replies but plan to check back periodically when I can remember to answer questions. I wish I'd have known all of this going into the project, hopefully it helps you!
Other considerations for longevity:
If you have an old truck like mine, consider getting a tune up and new distributor cap. You might also change the O2 sensors, I found mine went bad without giving me an engine light. It killed my power and drove me crazy. There is also an inlet at the top of the engine toward the back that will be brittle and break soon, leaking coolant on the ground. Have a shop handle it when it happens, trust me. Also, you might check the circuit board for the windshield wipers if they ever go intermittent or quit.