4.0 5 speed 4 wheel drive question?

[hockey4704]

i have a 1992 ford explorer and it has sat for a couple of months, and i started it and ran it, and when i was checking to see if the four wheel drive works and it gave me a little bit of a problem. first it went in 4 wheel drive fine but when i started to move i herd a thumping noise comming from the rear for about 50 feet but then it went away, i dont know it the fluid needed to get there to lubricate it or what but it did go away. And also for the main problem, when i was trying to take it out of four wheel drive and i had a hard time, i pushed the electornic controlled 4 wheel drive button so it read it was out of 4 wheel drive, then i put it in reverse and rolled it back a couple of feet to disengage it and then it felt like it was kind of stuck in the middle, because after that it would drive like the e-brake was on but it wasent. so i drove it around and i was playing around with the 4 wheel drive trying to get it out and it made a loud clunk and it came out. does any on have any answers to why it did that. i would love to hear your opinions about it , thank you!!