Ok, I have an 86 samurai that is making a grinding noise in 4wd. Everything is fine in 2wd, no noise. I can accelerate in 4 High with no noise but as soon as I coast it makes a very noticeable metal on metal/grinding noise that is relative to the speed. Clutch in or out, same noise. Trans in gear or neutral, same noise. If I step on the brakes I can get it to change or go away for a second. So far I've gotten under the truck and checked all driveshafts and U joints for play and all are seem tight and in good condition. I swapped transfer cases with a used one with no change. Changed fluid in trans, t-case and front and rear diffs. All looked good, no milky fluids or metal shavings. I am under the assumption that there is something bad in the front axles, differential, wheel bearings, birfield joints, or hubs? I am not familiar with working on solid axles at all and am not sure how to proceed at this point. If anyone has any ideas I would surely appreciate it!