Arnold's wildest dream is realized when he comes face-to-knee with ""The Champ"" -- special guest star Muhammad Ali. When the meeting arranged by Mr. Drummond between Arnold and his idol, Muhammad Ali, falls through, Kimberly and Willis concoct a wild scheme to insure that Arnold's dream will come true.

The Drummond family celebrates the day Arnold and Willis are supposed to be officially adopted until the visit of a ""relative"" leaves their plans in jeopardy. Whitman Mayo guest stars as Jethro Simpson, who sees his way to go from junk to jewels in a last will and testament leaving a fortune to Willis and Arnold.

Their family and friends assembled, Phillip and Maggie meet at the altar, only to realize each has made a major mistake, in the concluding part of a special two-part story. Charlotte Rae, Dody Goodman, Janet Jackson and Nedra Volz, each of who had appeared in recurring roles on ""Diff'rent Strokes,"" return as their original characters for the Drummond nuptials.