As far as the spool in the front, I don't know much about those or the lockrites. What does the spool in the front do, and is the lockrite more of a posi trac or limited slip or neither?
This topic has been covered many times, so do a search for a more therough answer, but there goes....
Good: Spools, or welded gears (aka lincoln locker, welded diff etc)
A spool is true posi trac. The right and left wheels spin at the same rate. This is EXELLENT for trails, but can cause problems on the street. The tires "fight" each other in a turn (since the inside tire is turning less quickly than the outside tire) - the thing that ends up relieving this pressure is your tires... which eats them up faster. You'll also have to SLOW DOWN in wet / icy road conditions... or you'll spin out. Spools are available for $100. Welded diffs are free... provided you know someone with a welder. It does the same thing as a spool.
Better: Lockrites, or EZ Lockers. Stay away from EZ Locker brand. I've never heard of a Lockrite failing (and they cost the same, so it's a no-brainer). These are mechanical limited slips. During normal driving, they should allow your wheels to do what they need to do, and save your tires. There will be lots of clicking and poping sounds in turns - you'll get used to it. You'll need to slow down in wet / icy road conditions or you'll spin out. $200.
Limited slips are out there, but stay away from them as they'll just burn out with trail use.
Best: ARB or Electronic lockers. These are "selectable" lockers. They're open diffs for daily driving, and you flip a switch to lock them for the trail (or to get your trailer out of the mud). These are the premium way to go, but they're also $1000.... to me they aren't worth 5 to 10x the cost of a spool or mechanical locker. I can think of a lot of cool things that extra $800 (per diff) can get me. I'd go with the electronic locker (personal pref) because the people selling them right now are also including some really strong axle shafts (manufacturer is claiming they're bulletproof).
I suggested spool in front 'cause you'll only have the front locked when you need it, so $100 and you're done. I think a lockrite in the back 'cause it'll save your tires for when you're on the street.
Some people will suggest different configurations. Each one has their pro's / con's.
I ended up having to use a come-along to pull myself out of the hole that the trailer sunk into. I know it was wet, and a little bit of a hill, but I bet if I was locked, I could have pulled it all out no problem.
That, and tires. Street tires don't get much grip off-pavement.
As far as the shackle reversal kit, I don't know how those work.
Again - search, or check calmini's web site.
I envision a friend of mines 73 ventura with extended shackles and thought it looked cheap.
Extended shackles are cheap, but I won't even consider them an option. They suck... really bad. I'd look into (in order of lightest cost / lift): Shackle reversal, Rears Up front, YJ SPUA, YJ SPOA. Each step up is a step up in cost and difficulty. If you have tools, and are willing to wrench the shackle reversal from calmini is easy to bolt on, a complete kit, cheap and will improve your ride quality while providing you with 2" of lift.
Be warned now that MOST kits out there (other than Calmini) are not truely "complete". Once you start going SPOA, MOST kits are missing SOMETHING (extended break lines, extended shocks, driveline spacers, new upper and lower shock mounts, steering correction.... the list goes on....). Calmini is not the "best", but they're good kits, and almost always complete solutions, and they offer more bolt-on solutions than most. I wish more manufacturers would follow suit. If you're a novice, and not going to do super-extreme rock crawling, Calmini is the only way to fly (for that matter, I know several people who have calmini's BIG lift kit, and they go to the Rubicon regularly).
Maybe the kit you're talking about is different. Do they look good or jury-rigged. Do you lose stability?
I didn't suggest a shackle extension, I suggested a shackle reversal. Again - see calmini's site for explination on why this is so important for ride quality. As far as looks, that's always a personal pref thing.
I may need some sort of recipe for this so I don't keep opening cans of worms!
I understand that in the begining it's hard, as you're not really sure what you're looking for. But, if you check out the FAQ's, and do searches on "lift kits" and such - you'll glean a lot of information. Believe it or not, you're not the first person to ask about lift kits
-Jeremiah