Before the merger with North American Aviation, Rockwell made truck axles and other automotive products.
While not exactly a spinoff, Boeing has done well after acquiring Rockwell's aviation assets which ROK stockholders received Boeing stock for.
I don't know about AT&T. I inherited a little AT&T from my mother which I still own. I figure I didn't pay for it and it pays a good dividend. I don't own enough to worry about.
ROK evolved from a company that made airplanes, Apollo space capsules, and truck parts to what it is today which isn't even close to the same line of business.