By Robert Irvin UPS Automotive Editor DETROIT UPI) — American ‘carmakers work years ahead in planning the new modes they in troduce each fall .The 1963 models which will be ‘keen in September are “old” cars to the engineers, stylists and pro duct planning people at the auto] ‘companies ‘They finished with those models long ago. Now they are locking up many plans for the 1964 cars Tooling orders already are being’ made for '64. One line, the Chevy Tl, may be dropped. Ford, is planning major body shell changes. Perhaps because of this, Ford is already two months behind in ordering tools for the “oH cars ‘Big changes are expected, 100 at Chrysler. The 194 models wil be the first that the firm's new life stylist, Elwood Engle, had a fall crack at. Look for new body Bhel is here, too, Engle, who styled the Lincoln Continental when he worked at Ford, joined Chrysler last Decem ber. ‘Because of the long lead time required to bring out a com pletely new car, Engle was a ble to make wholesale changes in the ° 6) Chrysler models ‘American Motors wil bring off a completely new Rambler Amer ican in 1964, with the wheelbase | Temgtened from 100 4 108 inches | ‘The trend toward larger cars will start ‘with the 193) models Tr wil be even more pronounced | in 1968 General Motors, which plans extensive bodyshell changes through all divisions, appears ready to drop its compact size Chevy II line of cars in 1964 .The Chevrolet division now has four lines, the Corvette sports| + car, the standard Chevrolet, and two compacts, the rear- engine Corvair and the front - engine Chevy I .The Corvette gets its major overhaul in 1968. The new model, called the Corvette Sting Ray and closely resembling an exper imental car of the same name, will be relatively unchanged for um .The big changes will be in the passenger cars. The Corvair will get a new body and will remain a combination compact and low price sports car. Replacing the Chevrol—which may be heard from again if the tools and stampings are sent to GM of Argentina as rumored— will be a new line sized with the ‘3 Ford Fairlane, Buick Special, Olds F-45 and Pontiac Tempest .This will become the standard sized Chevrolet and the series models will take the names of the faresent big Chevys—Impala, Bel Air and possibly Biscayne al though the latter name may be trapped .On top of this line will be a new line of cars—as yet unn amed—from 5 to 10 inches big er than the present top line Some sources say the line would compete with the big Olds $8 and Buick Electra, ‘Other sources say the new top Chevy line will be built on an Olds 88 chassis—a little smaller than the “98 —and would use t lunder components from the 88” series such as spring and suspen sion systems. ‘The Chevy 11, brought out last fall, is doing well, is expected to sell 400,000 units’ in the current model year, and in June was the No. 2 compact, with 38,195 sales to pace-setting Rambler's 45,115.| Falcon was third with 31,766 and | Corvair fourth with 3,429 ‘The reason for the big changes ‘now planned apparently is this: | Sarmakers feel the swing in| customer preference is back to bigger cars. Compacts will contin ue to grab a large share of the | market, but they won't reach the | 50 per cent figure once estimated by ‘some industry executives