i heard of problems with 4.88 gears in a front D30 with manual tranny.
only 2-3 tooth of the ring and pinion have contact. and the torque peaks that you have with a manual tranny (not with an auto tranny) could be too much for that.
do you have a rear D35? then 35s or 36s are too much when you want to do some real offroading.