1988 Chevy K2500 4X4 Lo Will not engage?

[123]

Hi I just recentlly purchesed a 1988 Chevy K2500 4X4 350 5.7l with a 3 spd with low range i am new to 4wd i do not have the front shaft in it right now the reason is sitting still I can get the lever on the floor to go into 4 hi but i can not get the lever to go in to 4 lo any ideas on what is wrong or what is proper way to to engage 4wd lo

 

[Doc]

I had a similiar problem when I first got my 96' k2500. I usually put it in park to shift from 2 to 4 wheel, but my 4 low wouldn't work unless I put the transmission in nuetral and then push the 4 low button, if you havn't already tried that.