How did Walter Radar O'Reilly die in MASH 4077?

I do not believe that Radar died at all. If I am not mistaken, he survived the war and was in an episode or two of the ill-fated 'AfterMASH' spin-off with Potter, Klinger and Father Mulcahy.

Radar's uncle Ed died, leaving his mum alone to run the farm. This was grounds for a hardship discharge from the army. He was wounded once in the episode "fallen idol" season 6, and in other episodes, bitten by a dog for which he got rabies shots and had a tonsillectomy, all requiring him to be hospitalised at the 4077 - but he never died in the series.