If your talking about pulling a front end out of a mustang or pinto for an AD I agree they may be a little light for a 1.5 ton that carries logs out of the forest.
Most ADs with IFS are not hauling loads. Additionally they probably have a sbc V8 in there which is some 80 lbs. lighter than the original 6 cyl. If their IFS is from a reputable company like TCI or Heidts which is designed to work in their particular application and is installed according to the mfg. directions it will be as dependable as any Detroit design.
My 2 cents...
