Personally, I love the Explorer leaves. With 3 dirt bikes in the back, it doesn't sag nearly as much as other Ranger that I have seen, do.
And I wheel the hell out of mine. They flex pretty well too! here's a couple pics:
The only reason I would not do the Explorer leafs, is the fact that even with a leveling kit, it will still probably have more of a rake than it did from the factory, with no load. But, if you regularly haul tools or something in the bed, I think you would be better off than no weight.
If you are hauling 3-400 pounds in the bed, I don't think you would have any problems, except maybe slightly poor fuel milage due to the weight.
I guess my first question SHOULD have been, does your truck have a rake to it right now? If it does, then the Explorer leaves will make it worse, without a leving kit, and even then it will still probably be slightly higher than a factory rake.
But if your truck does not have a rake (I don't think 2wd ever did) then the Explorer leaves, I would think, would put your at roughly a factory 4wd rake, maybe slightly more.
This is what my Ranger looked like with the Explorer leaves, and NO leveling kit:
vs with the leveling kit:
There is a differance between the blocks you get in a lift, and the blocks that alot of Rangers/ B-series had from the factory. First of all, if you look at your rear axle, and between the leaf spring, and the axle house you this:
http://www.therangerstation.com/Magazine/Summer2003/images/FactoryBlock.jpg
the you already have factory blocks.
These are aftermarket lift blocks:
https://www.ultimateautoaccessories.com/Merchant2/graphics/00000001/SuperLift-Block-Kit.jpg They are do the same thign as the factory ones, but you will pay alot more for them than you would for factory ones from a wrecking yard.
Aftermarket blocks would work for you if you have a 2wd, but I think you'd be better off with the stock blocks.
Here's a couple links that might help you too:
http://www.therangerstation.com/Magazine/Summer2003/LiftingOnABudget.htm
http://www.therangerstation.com/tech_library/ExplorerLeafs.htm
Those both came form the tech library