Costell's innovations took him from sales manager of one circle to all three. The Costell Sell   (cont'd) Aggressive, do-anything-for-the-close salespeople don't rate with Josh Costell, whose theories won him a big job. By BETSY GIBSON Associate Editor     Josh Costell didn't want to talk about himself. Not that he's shy about personal topics, but because denigrating conventional sales tactics that focus more on product than customer excites him far more. He laughs and says that he'd happily credit a magnetic personality for his recent appointment, at only 30 years old, to national sales manager of York Air Conditioning's Engineered Machinery Division at York, PA. But it really happened because he found a new way for the division to sell, replacing tactics with strategy - an innovation he discovered when, at 24, he rejected colleagues' explanations that "you're a high-energy, personality" as flattering but empty.     Previously, as national sales manager of York's Maintenance and Energy Services Group, an arm of the division he now heads, Costell built a sales force from 6 to more than 50 and doubled the close ratio from 3 out of every 10 jobs quoted (the industry average) to 6 out of every 10. It all happened because he dissected rather than accepted his early success, asking customers why they gave him one contract and not another, searching for why one sale took two weeks while a seemingly identical one took five. Costell, a tall, lean man with a twinkle in his eye, remembers that, in the beginning, "Selling was like having a lock to open. I listened and happened to choose the right tumblers. But I didn't want the tension of picking a lock each time. Somewhere there was a combination, like eight-six-twelve, which would open the sale automatically."     Such a metaphor is in character. Costell was always taken with numbers, no doubt the foundation of his exceptionally logical, goal-oriented approach to problems. This orientation led him to expose the illogic of classic sales techniques just as, at 19; he dared question the path of medical or law school expected of him. His father's reaction was "Then you're on your own financially," Costell left a comfortable Long Island home for Florida. By day he dug ditches with men so macho they wouldn't even wear gloves. By night he attended community college with "swollen roast beef hands." Contrasting the finite limits of his body with his brain was what Costell needed to clarify his objective, and in short order he graduated from the University of Florida with a 3.7 grade average in management. A few years later he'd refute that same kind of macho gloves-off mentality of asking salespeople to prove their mettle by trying to sell ice to Eskimos.