There's plenty to work with there, it's possible someone modified the pack to what you see now. It's up to you, this project may be more trial and error since we don't know what it is but it's really up to you. For sure the overload spring needs to come off and then another leaf or two Depending on what you're trying to get to (height wise) and if you want to run blocks or not.

Those springs look like C code. If you don't want them then I'll take them..

I don't think those are C codes. C, S, V codes all have a helper at the bottom, Excursion is the only one that doesn't. It's possible it is/was a super duty spring pack with the lower aux removed. Hard to say what it really is at this time...

V codes are a front spring and never seen them with a helper spring from the factory. Did you mean B code?

I'm gonna make them work somehow. Probably take out a leaf or two and definitely the one off the top.

I just looked at my OEM B code springs on my 02 SRW F350 and I have 4 leafs, 1 helper and 1 overload spring. Mine have never been removed from my truck. In the pics on page 1 there are 10 leafs and 1 overload spring which is why I said those must be C codes that where on a DRW F350 or higher.

Yes, sorry, I did mean B code. Thanks for catching it!

Anyone have an idea on the best way to modify the rears?

So looks like I have f-450 springs from my Internet research. They were the only springs that I could find that had 11 leaves in the pack. Must have been an option for heavy duty towing on a f350. Should I try these as is or take a few leaves out? Also if I leave as is should I add a 2" shackle to the fronts? And last but not least, did you change out the bushings in the springs when you swapped them?

If you want a stiff ride then leave them as is. Otherwise you can take out a couple leafs and go from there. I would think you would have to add some shackles to the front if you left the rears alone.

I've looked all over for a rear sway bar install write up but I can't find one. Pretty sure I'm going to try and tackle everything this weekend and am pretty confident about the spring swap but not sure about the sway bar install since I'm not replacing one, I'm adding it.

sway bar install
 

If you just set the bar over the driveshaft/ differential, you'll see where the 'U' brackets go in the grooves that are cast into the diff housing. Then the end rods (that go up to the frame) will land near the holes in the frame to bolt to. Easiest install ever!

I just remembered- the passenger side rear shock mount has a plate on the front side that needs to be trimmed down so the sway bar will clear. You'll see when you have things sitting there. Good Luck!