This is BRAND NEW in the box - set of Heavy Duty Stainless Steel headers. Available for: 1955 - 1956 - 1957 Chevy Belair - 210 - 150 - Wagon - Nomad - Full size passenger Cars. These really are the best headers for your TRI 5. The heavy duty design will allow you to FEEL a HUGE DIFFERENCE!! With the sky rocketing gas prices, these will help improve your gas mileage. Along with those savings, you will also add Horsepower!! Fits small block Chevy. Application Info: 1 5/8" primary heavy duty tubes 3" Collectors 3/8" Flanges Fits the following Sm. Block Engines: 283 302 305 307 327 350 400 Note: With most exhaust jobs, some slight exhaust modifications may be necessary. Includes: Headers Gaskets Collector Flanges All Hardware Instructions Brand new set of Stainless Steel Tri Shorty Headers. Fits 1955-57 Small Block Chevy with original steering box or the popular GM 605 steering boxes. They also fits stock front or side motor mounts. The passenger side header is much short to clear the idler arm. Stainless Steel 16 Gauge Tubing. Flanges are 3/8" thick. Tubes are 1 5/8". Collector is 2 1/2". Work with both angle plugs and straight plug. All the necessary install hardwares are included. ( bolts, gaskets, and collectors. ) NOTE: It is not for use on pollution controlled vehicles. Minor modifications may be required for certain models. These headers will not work on the passenger side if you use edelbrock aluminum heads. The inside of the 4 exhust hit the head bolts. Professional installation highly recommended!!! No instructions included! If your vehicle is using aftermarket components, parts from other applications, or custom-altered parts, then it is the installer's responsibility to verify fitment.