Clunking in 4lo

Clunking in 4lo not sure what it is. 4hi seems to work good but 4lo doesn't. It is on a 1995 Sport, manual, guessing it is the np231 not sure, 4 inch lift, 31's. When I put it in 4lo it doesn't stay in gauged and I have to hold it in. Than when I put it in first and take off it starts clunking. Sounds like it is coming from the front drive shaft. Any Ideas?

Mike

have you tried to re adjust the shift linkage? sounds like its not fully engaging. dumb question, but are you sure the clunking isnt from the u-joints.

lube the linkage.