Our resident lax experts Dave Coleman and Steve Holroyd ("Two for the Show") return to help us dig deeper into the largely untold story of the original National Lacrosse League - the seminal mid-70s indoor circuit that helped lay the groundwork for modern-day professionalization of one of North America's oldest organized sports.   Originally conceived by NHL hockey owners as a means of filling their arenas in the off-season summer months, the NLL consisted of six clubs in each of its 1974 (Maryland Arrows, Montreal Quebecois, Philadelphia Wings, Rochester Griffins, Syracuse Stingers, Toronto Tomahawks) and 1975 (Maryland, Montreal, Philadelphia - and the relocated Long Island Tomahawks, Quebec Caribous, and Boston Bolts) season.   While sizable crowds flocked to the league's fast-paced, rough-and-tumble summertime box lacrosse action in Philadelphia, suburban DC's Landover, Maryland, and Montreal - the NLL's other franchises found the going much tougher.    When it came time for a planned third season in 1976, however, three of the league's six clubs were already bankrupt, and the Quebecois were rendered homeless by the Montreal Summer Olympics, which had annexed the Forum as its boxing venue.   There would not be another professional lacrosse league in North America until the birth of the Eagle Pro Box League in January 1987 - the precursor to today's NLL.