I just noticed the left rear spring mount is cracked. What's involved with the R&R of this part? How much should the job cost me?

 

If its riveted in (some are bolted) it requires grinding chiseling, whatever them out and removing the old and bolting in a new. The bigger problem can be getting the bolt out of the eye of the shackle. They tend to "grow" to the bushing over the years. All in all not too difficult as long as you have a safe way of supporting the truck while you do the work.

 

I've done this on that very same spring hanger. The part is about $45 (IIRC) from JBG and it takes some work.

Assuming that you are doing the rear hanger (between the axle and the bumper), here's how I did it: First you need to get the spring bolt out, which can be hard depending on what kind of weather the truck has seen. Then, you'll need to take a sawzall (worked better for me than a cutting wheel) and cut as much of the old bracket off as you can. If there's any left sticking out, use a heavy hammer to pound it flat. If you know how to drop the gas tank, do it. That will make things a lot easier (and somewhat safer). Now you need a grinder to get the rivet heads off. Some people recommend chiseling them off with an air hammer, but that didn't work for me (I tried). I just bought a decent electric grinder and a few course discs and ground away. Keep in mind that the metal you're grinding off will be showering down on you in the form of really hot slivers, so wear protection. Grind all 4 rivet heads below flush if possible. Now you either need to pop the rivets out with an air hammer or use a spkie and a heavy hammer to punch them out. Air hammer works nicely, so if you've got one, use that. Sand and prime the area, throw some sealant on there if you like... and bolt on the new hangar using grade 8 bolts, lock washers, and nuts (available at lowes or home depot). If you were able to save the old bushings and bolt from the spring... you just bolt it up as it was before. I'd recommend getting new ones anyway since they are cheap, but that's up to you.

This can all be done in one saturday pretty easily if you have the tools. For less than the cost of the tools, you can probably have your local body shop do it for you... but then you don't have the new tools

 

I torched the rivot heads off, Hardest part was dropping the tank enough to get in behind to get the nuts started.

 

yea, if the spring bolt is stuck, it can be a pain to get out, did it on my old F150, and just recently did it on my 93 lightning.
i drilled it out, till there was like a moon shaped peice of the bolt, and then went behind with an impact gun, and turned it loose, then hammered it out