Dutch--you really put me to shame. The first new vehicle I bought was a 1979 Chevy Monza 2+2 hatchback with that very same 2.5 liter (aka 151) inline 4 engine. I found out a year after I bought it that it was a Pontiac engine; they used them in Chevy Monzas, Buick Skyhawks, Plymouth Astres, Pontiac Sunbirds, what have you. I'd be more than willing to sell you mine, but I traded in my '79 in October 1990 after 222,822 (more or less) worry-free miles. I NEVER had any mechanical problems with that engine, never had anything done other than replacing several oil seals at the 100k mark. Other than replacing the carb at 150k and the clutch at 172k, and upteen sets of tires, that car more than paid for its $5800 sticker price. I am not surprised that you got 635000 miles out of it, congratulations. You might let me know if your vehicle had a 4 or 5 speed trans in it. My Chevy had a 4 speed and that was the only thing I didn't like about it, I couldn't shift into 4th gear any slower than 40 mph or the engine would start to lug.
