What type of exhaust does your 273 have??? show some photos!!!

66 Dart V8 273 - 4 speed mec
Ah sorry. I didn't remember you from your other thread. The most correct system you can buy is the Accurate HP single system. Something to know if you are thinking about a dual pipe system, the transmission crossmember is designed for a single pipe on the drivers side. The crossmember can be modified to accept a right side pipe or a custom bent pipe can go below the crossmember. Not the neatest install but the only way to do it.
Dual Exhaust Crossmember Modification on 64-66 A-Bodies?