Mile marker used to sell a parttime kit.
My 79 Trailduster had it.
Never changed anything other than that. Gave 2hi 2 low 4 hi and 4low.
I always loved the Dodge fulltime 4x4 so I hated this mod...but I guess it gave a 1mpg gain.
The full time 4x4 is very good. I would just leave it alone. The only thing you can not do with it is a burn out.
It works great in all weather situations.
My opinion keep it.
If you decide to chanfe there are a few options. 1980 was the first year for the part time. You could do a swap from them...but they are hard to find
Also the part time trucks go to the 5 x 5.5 bolt pattern from the 5 x 4.5 found on your truck.
So if you are planning to use something newer you will have the 2 bolt patterns
If you are going to do it...to gain the most improvement, you will have to go with manual hubs...but you can keep the original setup and be fine.