I was needing to know if anybody good come up with a good diagram of how a 203 works specifically, I understand that it is Fulltime 4wd, I just can't get my buddy believing me, he thinks it is 4L 2L N 2H 4H. I think he'll believe me if I can get a diagram showing the differential gearset and all of the workings.
Thanks for the help,
Scott

 

I don't have any tear-down pics of a 203 or a tech drawing of it. Here's an explanation of how it works:

The shift pattern is Hi-Loc, High, Neutral, Low, Lo-Loc (or vice-versa, it's been a while since I had a truck with a 203 in it). The High and Low positions are still 4wd, but they are safe for use on pavement. The Loc positions are not for pavement use.

The t-case has a central differential that allows it to be in 4wd all the time. The case is 2 seperate parts. The first part is the 'range box', which contains the low gear, which is 2.02:1. The second part is the 4wd part that drives the front shaft and contains the differential. The front shaft is chain driven, unlike an NP205 which is gear driven. Moving the lever to either of the Loc positions locks the central differential so it becomes like a spool, locking the front and rear output shafts together like an axle with welded spiders or a spool.

The differential can be defeated with a part-time 4wd kit that permanently locks it. Another style of part-time kit for the 203 replaces the differential altogether with something similar to a spool. I am unsure on exactly how the front shaft disenagement is provided for, for operation in part-time, but it is provided for.

The 'range box' portion of the t-case can be split from the 4wd portion of it. This range box can then be bolted to the back of a transmission and the front of another t-case, like an NP205 or a Dana 20, with the proper custom adapters (which are now available in kit form) for use as a double-reduction auxilliary transmission for rock crawling, and other low-gear operations.

Good luck convincing your buddy!