This might be of interest:
https://www.gmheritagecenter.com/doc...-El-Camino.pdf
You might find that it is a 229 Chevrolet V-6, or a 262 V-6, and not a 231 Buick V-6. There are substantial differences, but it could be any one of many engines. I had an '80 Malibu wagon with the 229 driveline.