Hey Gus thanks, very close to my problem, but dont have any issue with 4H thats as solid as ya get never pops out, 4L does pop out under load but stays out. Diff doesnt make any popping noise either.
Did have the front acuator pump issue which i replaced, when replaced sealed up the pump good with black silicon to stop water getting in it. Still works properly.
Replacing the transfer is a option, but just hopefull it was a easy fix

was hoping after cleaning the crap out of the selector which allowed me to drive over some large rocks it was good, but that soon came to a end when got bogged in sand.
I also have a feeling that the front transfer seal is stuffed as there is oil on the trans around the location of the Front shaft, but no actual signs of leaks on the transmission.
If did go for a new transfer, is the case the same as a GV?, in the manual there has been a few different transmissions.