An old promotion pays off.

We didn't know what to expect," says John Harvey, of the Du Pont launch of a promotional "Classic Farm Tractor Calendar" for the year 1990.

The calendar was simple: pictures of 14 mint-condition tractors of various makes and models, and some verbiage touting Du Pont Classic and Accent herbicides. Tractors were not the original choice of a theme - the initial thought was to do a classic car calendar. But tractors were finally chosen because they had a "more agricultural flavor," explained Harvey, a Du Pont communications program manager.

"Some of the non-farm marketing communications people at Du Pont were flabbergasted that commercial farmers - our customers - were interested in these old rigs," he said. "But they had not grown up on farms and had no affinity to tractors.

"Our market research showed us that many of our power buyers - established farmers who make a majority of the buying decisions - are 50 years of age, or older. I felt this age group would respond favorably to antique tractors. Most of them could identify with tractors built in the 1930s as one their fathers and granddads farmed with, and that they learned on.

"I also did some research on my own and determined that |old iron fever' was rampant, and was spreading."

Beside achieving Du Pont's goal of getting its products' names hung in homes and workshops through the nation's farms, the calendar has boosted company promotions at farm shows.

Large crowds came to the Du Pont tent at big shows like the Ohio Farm Science Review and the Farm Progress Show to gaze at some of the tractors featured in the 1990 calendar. The Illinois Corn Growers Association featured several of the tractors at its annual meeting and trade show.

Du Pont, working with Goodyear Tire & Rubber, put five of the tractors on display at a tractor restoration workshop at Lake FarmPark in Kirtland, Ohio, last August. More than 2,500 paid visitors - primarily non-farm people from the Cleveland area - attended, and viewed the Du Pont tractors. More than 50 people attended technical workshops on renovation techniques. Now Du Pont and Goodyear are considering sponsoring similar workshops in the near future.

While it's difficult to draw a direct relation between the calendar and sales of Classic and Accent herbicides, Harvey said Du Pont research showed a high awareness of the calendar among farmers, and most identified Du Pont as the sponsor. Financially, sales of the calendar helped the project break even in the first year, even with many calendars given away free.

What drives farmers to pay good money so they can hang an advertisement on their walls, and refer to it frequently?

Clyde Berkshire, a former International Harvester farm machinery dealer in Royal Center, Ind., caught the restoration bug years ago, and now deals with victims of "old iron fever" from his Cub Cadet lawn and garden dealership that is also a parts source for restorers.

"I get 100 calls every week from across the United States, and sometimes calls from Canada, Finland, England and Australia," Berkshire said. All the calls are for parts for IH equipment, which he sold for 37 years.

Over the years, he said, he bought out about 100 dealers and stockpiled their parts, originally thinking he would use the inventory himself. But now he's selling it off.

Some of the parts, though, go to his own restoration projects. He owns 50 to 60 tractors, and has restored about half of them. His collection also includes some 25 trucks and 4,000 toys.

Another business built on old tractor parts is The Depot at Chilton, Wis., with a $24 million inventory of old parts spread over 80,000 square feet in 3 warehouses.

Steve Cullen, president and general manager, says The Depot will sell only to dealers, not retail end-users, and works only with manufacturers' part numbers.

"We must know the actual parts number," he said. "Just giving the model number, year and serial number doesn't do any good. Most retail users don't have any idea what the part number is, or what they would need.

"There are 12 dealers in the United States that I know of who really do take the time to work with the restorer. When someone goes into a dealership and talks to a lot of parts people around the country, the machinery is 30 years older than the person behind the counter."

Older tractor models, he said, would make sudden and drastic changes in components - those familiar only with modern equipment may not realize that.

"Unless you have a really good parts man," he said, "there's a good chance he'll order wrong. Old parts managers used to know what type of parts they were by looking at them, not by parts numbers. It's not like today where you deal with a computer. Younger people today don't know which way to turn."

Alan Smith, a McHenry, Ill., trucker/excavator whose tractor is on the cover for the 1992 calendar, said there is a relatively good supply of parts available for his bright red 1941 Farmall MD, since about 390,000 M model tractors were made, and many are still in use.

His biggest problem, he said, was ordering parts.

"It seems like the dealers don't really want to spend much time on old stuff where the parts are hard to find," Smith said. "I can find the parts better than the dealers can."

After finding the number of a needed part, Smith would often order it from The Depot, placing the order through the George Freund Equipment dealership in McHenry.

Smith's "cover girl" tractor is the result of an immense labor of love.

"I had every nut and bolt off it," he recalled. "I tore apart 4 other old M gas tractors. I took the best gears and shafts out. I put in new seals and bearings. The motor was completely rebuilt with new parts."

His machine isn't just any old tractor, but sort of the girl next door. His neighbor, Clint Raven, bought the tractor in 1941 in Wauconda, Ill., and used it for many years in custom farm work, from plowing and thrashing to filling silos and combining oats.

The tractor was eventually sold, and Smith traced it through northern Illinois and southern Wisconsin, and finally bought it from a farmer in Monroe, Wis.

"I had a lot of respect for the guy that used to own it," he said. "It was the first. I've always liked that tractor."

Harvey, the Du Pont marketer who had faith in the promotional value of the calendar, has his own explanation of why marketing with old farm machinery seems to have such appeal.

"I like to say that a man never forgets the first girl he ever kissed, nor the first tractor he ever drove."