Here are my favorite episodes that aired during the month of March in each season. Two or three seasons aired only one or two episodes in March, so I listed it / one of those. Why not pick out some to watch this weekend.
Season 1 - March 2, 1969 - Six Kilos
Season 2 - March 4, 1970 - Three Dead Cows at Makapuu, part 2
Season 3 - March 3 and 10, 1971 - The Grandstand Play (only episodes aired in
Season 4 - March 7, 1972 - R&R&R (only episode aired in March)
Season 5 - March 6, 1973 - The Diamond that Nobody Stole