Strange popping noise when 4x4 engaged

My 91 b26i 4x4 has a popping noise when I try to turn in 4x4. Is it the hubs not biting on or something else?

CV problem?
Easiest thing I can think of might be a loose sway bar, but that'd clunk when in 2wd too
Can you disengage the hubs while in 4wd?
If so, do that and try turning and see if anything changes, if it doesn't it's not the hubs (or less likely).
Where are our 4wd guru's
oh! it may also be your solenoids not getting enough power etc etc and not engaging.
Is your 4wd actually working?

It engages properly and i can hear the hubs going over but I'm not sure if they're biting on haha. Or could it also be ball joints needing replaced? I know it needs new CV axles and such