Can you see if there has been any work done to my heads?

PanGasket said
I agree on the hardened seats note, I was always taught that the lead in gas was there to soften the blow on the heads. Like if you had a hammer and wrapped the head in a towel, the blow would be softened. If you run unhardened seats, you should run lead additive.

I have a set of '79 318 smog heads on my engine. I have absolutely no clue how many miles are on them, but I can tell you it's probably a good lot of rough ones. When I brought em to my machinist, they were absolutely pristine. The seats had no wear and didn't even need to be touched. Only thing it really needed was guides.

1975 was the first year that leaded gas was started for cars. Anything newer than that should have harder seats than the '74 and earlier leaded cars. I know that 75 is the first year of the catalytic converters for cars.

I think trucks were later to be converted like 79 if I remember correctly. The 78 Lil Red Expresses didn't have much pollution controls, but 79 did finally get them. We had a 79 Warlock II that was an emissions unleaded vehicle.