Is it possible to replace a 88' GL-10's part-time 4wd automatic transmission with a dual range manual transmission with locking center differencial? Would it be terribly difficult? Thanks for any info.

yes it can be done.

not incredibly dificult. just need to find a good doner trany and all the needed parts including the shifter assy. cables linkages ect.

it should be a bolt on otherwise.

Some of us have done AT to MT swaps and its no piece of cake. You need to install another pedal on the assembly box.

Need to change the rear end to match ratios. Need to change tranny mounts and any other mounting needed. You also need to defeat the AT elec lock out switch.

Now, if your a ambitious person and want that MT tranny real bad, go for it.

Just my .02