check the spot weld on the 3rd member were the tubes go into it,it has holes so the tube can be welded in place.

looks for cracks around the tube and the tube itself,put a strieght edge on it to see if it has the duke boys bend to the whole axle housing

I had a 7 1/4 with the duke boys bend and it chewed the side gears and spider up then broke.

you could pull the cover and eyeball the pin and spider gears and have a looky see at the c- clips in the diff and side gear condition.

signs of wear will let you know how bad the tubes are bent,and maybe time to find another.

while your at it.measure it from wheel flange to wheel flange to see what will fit or swap in to it.

i have a couple 8 1/4s and 8 3/4s

how has the rest of it been running?