95 4x4 problem

just fixed a leak in the front diff. but now it seems i can only engage and dis engage 4hi and only in neutral, then shift in to drive and it engages and works fine. but shift on the fly and 4lo doesn't work any ideas?

What transfer case?
Do you have a matched set of tires?
Ford is the one that has shift on the fly.
A chev always shift before you get in the mud hole.
MT