It’s unlikely that the differential is or was welded, but entirely possible something broke internally, when these diffs lock up you get severe binding issues when you go to turn. I’ve had spider gears bust in one and it locked up solid.
Also check for equal free play in cv axles on both sides, remove the axle nuts and push the axle in and measure each side.
Also check for equal free play in cv axles on both sides, remove the axle nuts and push the axle in and measure each side.
