Hi,i want to get new headers for my truck(chevy silverado k2500 350 tbi engine model 1990) but i have hard time understand what summit writes at the applications.For example it says for hedman headers must modified rotary AC,or example 2, it gives 2 codes for the same header one with and one without air tubes.I dont know very good english and i cant understand technical forms.
Thank you for your time and help