Ford Motor Company has unleashed an all-out attack on Chevrolet to recapture its leadership in light-truck sales - even as both American vehicle manufacturers gang up on the imports.
Japanese minitruck sales have fallen off sharply with the introduction of compact-size trucks by both Chevrolet and Ford. The hotly contested, 25-percent tariff levied in 1980 on incoming light trucks has added as much as $1,000 to their cost, thus making them far less price-competitive with the domestics.
Also, the new Ford and Chevrolet small trucks, Ranger and S-10, are larger than the imports and have features - such as double-wall, cargo-box construction - that the imports lack.
In December, the month after the S-10 hit the road, imported truck sales were off 22 percent, compared with the same month a year ago. In April they were off 14 percent, and in May, 12 percent.
''In two months the domestics have taken 10 points off the imports,'' asserts Joseph A. Capolongo, head of the Ford truck division.
The two historic truck competitors are ''mixing it up'' with each other as well.
In the first three months of this year Chevrolet led Ford by 42,000 trucks. In April, however, Ford beat Chevrolet by 13,000, but in May the big GM division was back on top by 8,426.
Ford trucks have topped Chevrolet in sales the last five years - and have beaten Chevrolet in eight of the last 10 years, a sore point with General Motors.
In Boston for a regional stockholder briefing not long ago, GM chairman Roger Smith confidently predicted a ''Chevrolet year'' in light trucks, but Ford's Capolongo sniffs at the claim. GM got a big jump on Ford when it launched its Chevrolet S-10 compact truck last November, four months before Ford could get its Ranger out the door.
Too, GM has a wider choice of engines for its new compact pickup. The S-10, for example, has a diesel as well as a choice of 4-cylinder and 6-cylinder engines. Ford offers only 2-liter and 2.3-liter engines in the Ranger, both 4 -cylinder, although it will have a V-6 engine midway through the 1983-model year.
Ford, according to Mr. Capolongo, ''lost several years in diesel development because of its work on the PROCO (programmed-combustion) engine'' that the company finally pushed to the back shelf.
As a result Ford is ''playing catchup'' in light trucks.
Helping its thrust for the No. 1 spot, Ford will offer a crew cab (4-door) F-series pickup in the fall, as well as a Ranger 4x4 (with 4-wheel drive) and a brand-new Bronco.
''We'll also have chassis cabs for the body builders and commercial trade.'' he adds. ''The crew cab is going to help us get our leadership back.''
The F-series crew cab will have 6- and 8-cylinder engines available, including a 6.9-liter diesel built by International Harvester. ''It's a fundamental work truck, and we'll sell 10,000 to 12,000 a year,'' Capolongo predicts.
Ford has been out of the crew-cab market for the last three years.
The diesel will first be offered in manual-transmission pickups, and next spring it will be available in automatic-transmission pickups as well as Econoline vans.
''It has 160 horsepower, which we think will give us a plus against the Chevrolet diesel, which is 140 hp.
''Looking at the minitrucks built in Japan, Capolongo says: ''The Japanese trucks are built for Japanese people. We think US truck buyers want a little more legroom, hip room, shoulder room, and head room. So this is what Ford did with the Ranger.
''For the last 20 years the highest purchase motivation for a Ford F-series truck, according to Capolongo, has been durability. In the Ranger, durability is still No. 1, and fuel economy second, he reports.
''That's why the Ranger has twin I-beam, front suspension. The entire truck was designed around the front suspension.
''As a result, the Ranger is what Capolongo calls ''a working truck'' and not a ''car truck.
''Ford Motor Company did four market-research studies in two years for the Ranger. ''What people told us when they looked at some of our proposals was that they looked too much like a car. It doesn't look tough enough. They told us that over and over again - four times.'' It took five years to develop the Ranger.
''We're also looking at a super cab for the Ranger,'' says the Ford truck chief. ''We already have one in the F-series truck, in which there is space behind the front seat for an auxiliary seat and space to put things.
''Chevrolet doesn't have a super cab. Dodge has one, says Capolongo, ''but we're taking the business away from Dodge.
''In the F-series trucks, sales used to be 10 percent 6-cylinder engines and 90 percent V-8s. They now are 50-50.
''This fall we're putting a 460-cubic-inch engine back into the F-series pickup truck line,'' says Capolongo. The largest engine now available is the 400 . ''We took it out for a couple years because of fuel economy, but we got a lot of squawks. We estimate at least 25,000 people want it back.
''People who want power want power, and they don't care about fuel economy. So we're dropping the 400 and putting in the 460.
''As for the medium- and heavy-truck business as well as light trucks, ''it's a couple thousand here, 5,000 there, and 10,000 somewhere else,'' reports Capolongo. ''It took us a long time to understand that.
''Ford does a lot of work with body builders as well as the recreational-vehicle (RV) people.
The heavy-truck business has been growing swiftly over the past 10 years, while medium-truck sales have been falling off. ''I think it's a result of productivity,'' says the Ford truck leader. ''People are carrying more freight longer distances today.
''Looking at the European truckmakers now selling midrange rigs in the US -- Mercedes-Benz, Volvo, Iveco, and so forth - Capolongo says the Europeans came to the US when European demand dropped off.
Ford has offered a Caterpillar midrange truck diesel since 1967, and has sold some 200,000 so far. Ford, according to Capolongo, is the leader in the midrange-medium-truck diesel business.
Asked if Nissan will pick up any advantage by building its pickup truck in the US next year, the Ford truck chief replied: ''Instead of an advantage, it is about to increase its costs by building in the US.''
Meanwhile, the light-truck battle is building up heat.