The 1970 Chevelle shared many sheet metal body parts with the 1970 Buick Skylark GSX, both are GM automobiles and have interchangeable sheet metal. They're also the only 2 high performance muscle cars to share the same roofline. The 1970 Chevelle came in sport coupe, sport sedan, convertible, four-door sedan, a couple of wagons, and coupé utility (the El Camino) body styles. Only 3 of these (Malibu sport coupe, Malibu convertible and El Camino pickup) were available with a choice of one of 2 SS options; RPO Z25 with the SS 396 (402 cid) engine and RPO Z15 with the new 454 cid engine.
The base model was now simply called Chevelle (which causes confusion) in lieu of the former base 300 Deluxe, and was only as a Sport Coupe or four-door sedan. Up in Canada however, the base series retained its 300 Deluxe name, with appropriate badging on each front fender just behind the front wheel well. The hardtop, convertible, and sedan received the upgraded sheetmetal but the station wagons and El Camino retained the previous year sheetmetal panels (which went on for the next 2 model years).
Source: Wikipedia (original)