I looked into finding a selectable locker for the front of my Ranger a few years ago. The only thing I found was a complete kit made by Yukon. They had air, electric and manual kits at that time. It was not listed as fitting the front on a Ranger. I talked extensively with an engineer there and we came to the conclusion that it would probably work with some modification to the cover that came with the kit. The internals looked like they would work fine. It was the cover with the shifting mechanism that was the problem. The front cover on the Ranger fits so close to a cross member that modification to the cross member would probably also require modification. He said that if it didn't work, I would be out the cost of the kit which was not cheap.
I was very tempted to give it a try because I have access to a full machine shop and the tools need for the modifications. I was pretty confident I could make it work but it would take a lot of effort on my part. Then, Torsen came out with a unit for the front differential. That changed my plans and I immediately ordered the Torsen unit. I am very happy with that decision. It is not as good as a locker but the combination of Torsens front and rear work very well.
The front Torsen is not felt at all in 2WD with one exception. When it is cold (approximately 40 or lower) it creates a slight on center steering wheel sticking feel until it gets warmed up a little from driving (about 5 miles). Many people say they don't feel it but I am very sensitive to any kind of steering feedback after racing in SCCA over 30 years.
In 4WD the front Torsen wants to pull the steering to on center, especially under load. It is not problem though until you have to drive a long distance with a slight curve or side slope. Then the arms can begin to feel fatigued. With power steering, I have never reach a point of discomfort due to this.
I didn't want an automatic locker. I have used them for rear differentials in racing and know of their quirks. Not really a big issue but one caused me to spin out in the rain coming off a corner once and that was enough to turn me against them after using them for many years without a problem.