geez guys, why dont you let someone lowered answer the question...
First thing first, what year is your ranger?
If it is 98-04 ranger (non edge/4x4) then you have a control arm setup...
2inch drop: get a set of DJM Drop Coils
3inch Drop: get a set of belltech or chasis tech 3inch drop coils
4inch Drop: set of 2inch djm drop coils and DJM upper and lower control arms
5inch drop: 3inch drop coils and DJM upper/lower arms
6-7inch drop: well, thats up to you and thats alittle lower then most static drops will go...
2.5inch drop: flip rear hangers, for parts cost only (did mine for under 20)
2-4inch drop: flip kit (flips axle to over the leaf) and an adjustable lifting shackle (the flip kit is good for 5 and the shackle brings it back up to a total 2-4inch drop)
5inch drop: Flip kit
6-8inch drop: flip kit, and then blocks (goes between the leaf and flip kit, bigger the block, lower you go)
Now, to comment on what Pickupman92 said, an explorer axle swap requires the removal of your axle and gives you about a 4-5inch drop in the rear, as well as disc brakes... However, depending on what axle you have now, it might just be pointless to swap (cost wise) Not everyone wants to throw out 100-300 (depends on how cheap you get it) just to drop the REAR...
Let me know if there is anymore questions
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2004 Explorer Sport Trac XLT premium 4.0L auto 4wd
1995 Ranger XLT ext cab 3.0L auto 2wd
2005 Jeep Liberty Limited 3.7L auto 4wd
2001 Ranger XLT reg cab 2.3L auto 2wd--SOLD
1999 Ranger XLT reg cab 2.5L manual 2wd--SOLD