Hi, I am a professional certified mechanic, with an engineering background, and 35+ years experience. I will do my best to assist you. Also keep in mind I don't know if you are a pro or a novice so we may have to fine tune the answer. Feel free to add any additional info you feel is needed as we go on. Always keep in mind that I am here to help you with any questions.

73, to 77 El Caminos used the 8.5 inch rear end, and 70 to 81 Camaros used the 8.5 inch rear ends, so the answer is yes both should use the 8.5 inch rear ends. If you have any more questions, as always, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.

I do not get paid for my work unless I am given 3 - 5 stars/smile faces. If the answer is not clear, let me know what additional help you need, and I will assist you further. A bonus and positive feedback are always appreciated, good luck and Thanks.

I wanted to see if there was anything else I could help you with. I answered your question, and you rated bad service. Let me know if you have any additional questions. Good luck with it, and thanks for using Just Answer.