From another thread:
1991 2wd supercab w the v6 auto trans.
Since lil_Blue_Ford tagged me I'll add a few thoughts. Please note that while I have studied the TIB Ranger lowering and V8 swaps, I've never done it. I'm basically working on the same build as him.
Body clearance to engine/trans after drop?
Key to body clearance with these drops is engine mount selection. Probably your best "off the shelf" option is to use TIB Ranger 4.0L V6 mounts and Rick's Rangers adapter plates. You may still need to fold the firewall to floor pan seam and massage the firewall some for clearance. If you're going to have AC, notching/clearancing the HVAC plenum will be required. Unless you're body dropping the truck, your body to engine/transmission clearances will not be affected by lowering.
Too much squat look
That's all in the suspension, you'll be dragging the engine crossmember before you hit the engine or transmission. Keep in mind that when new the rear end of a Ranger sits 2-3" higher than the front. Current stance may vary depending on how much the suspension has sagged over time. Generally speaking dropping the rear 2" would make a Ranger sit about level.
Rear lowering with a flipped axle, you're looking at about 6" of drop from using the Explorer axle with your current springs, It might be closer to 4" drop if you use the explorer springs as they are a bit taller. Again, YMMV depending on how the suspensions have sagged.
When dropping the front and rear you'd noirmally be looking at a (front/rear) 0/2, 3/5, or 5/7 drop to be level.
You said that you don't want to lower the front at this time, so with a 6" drop you're looking at the front being about 4" higher than the rear. That's at the axles, due to angles it's going to be more extreme at the front and reat of the truck. To install the Explorer axle spring under (aka flipped) with minimal squat I'd recommend running the Explorer springs which will be closer to 4" drop. Then you've only got about a 2" difference.
I can't say exactly what your results may be, but an additional step you could take is to install a set of lift shackles. I've bought them in the past from the local parts store solds as Chevy lowering shackles, they lower a Chevy but lift a Ranger. These can get you about 1.5-2" of lift. Those with the Explorer springs would put you closer to a net 2-3" drop in the rear, which would be close to level. I also can't say how doing all of this is going to affect your pinion angle, that's kind of going to be trial and error.
If you go for the 6" drop in the rear you may be able to get away with low profile bump stops, but I'd probably be putting a notch on the short list if it were mine. With a large drop on an extended cab, something you need to pay particular attention to is driveshaft clearance to the back of the cab. I recall that back in the day a lot of guys had to tunnel the back of the cab for driveshaft clearance, but I don't recall how much drop that was associated with. I also seem to recall that the two piece driveshaft (ones with a carrier bearings) were not happy at the dropped height, likely due to angles.
At least half of what I wrote there is based on paper, not real life experience. What should be a 2" drop according to paper might only be a 1" drop on the vehicle, or it may be a 3" drop. Too many variables to speak in more than generalities.
Driveshaft?
On an extended cab, I wouldn't be surprised if the Explorer driveshaft needs to be lengthened. In fact I can say with some certainty that it will need to be. If you had a 4wd I'd recommend getting a later model Ranger extended cab driveshaft. All of the Extended cab Rangers had practically the same wheel base and transmission positioning, so the same driveshaft pretty much fits all of the 4wd extended cab Rangers and might be the same for the 2wd extended cab Rangers. Unfortunately, I don't know if the V6 autos and the 4R70W used the same transmission output yoke. Might be worth looking into anyway, if the length is right and you can swap the yoke with a conversion joint, it might be a cheaper and easier solution than having one made. If you go hunting for a used one, in 98 they ditched the carrierbearing on the 4wds, might have been the same on the 2wd.
As mentioned above, driveshaft angles and pinion angle may become an issue when lowering. It's kind of one of those things where you'll have to check it and see what angles you end up with.
Are you confused yet? I am and I wrote it, but hopefully that's just because it's 1am here.