One of the over 600 volunteers removes two cases of Thin Mints from one of the 36 semi-trailers that were each filled with 77,000 cases.   177 boxes of assorted Girl Scout cookies fill a van that will be delivering cookies to Troop #660 Brownies. 1,000 Girl Scout Troops picked up their pre-sold cookies.   Each case holds 12 boxes, a total of 924,000 boxes filled with cookies, were distributed to over 1,500 vehicles in one day.   Helen Whitelaw, Director of Sales and manager of today's cookie distribution rides in a golf cart with Bob Carlson, owner of Carlson Logistics, supplied the 36 semi-trailers filled with the case of cookies.   Over $3 million worth of cookies were picked