[mrein3]

When I was still wrenching - 20 years ago this August - EVERY old timer in the neighborhood had a GM with a 2.5 liter iron duke. Cutlass Calias', Celebrities, Pontiac Somethings. They were in everything. There are two notable things I remember about that engine.
1. You couldn't kill it.
2. EVERY one that had air conditioning - and they all did - would crack the hard aluminum hose off the back of the compressor. The shop I worked at had 5 stalls. Back then when doing AC work R12 was $1/pound and Al Gore hadn't yet scared the world about this man-made global warming crap. To do AC work like replacing a cracked/leaking hose you simply cracked open the system and let the R12 vent in the air slowly so no oil would come out with it. One day there were only two of us working for some reason. I had 4 stalls tied up with 2.5 liter GM products in various stages of getting the AC hose replaced.

Another time we couldn't get a hose delivered so I hopped in my car and drove down to Midway Chevrolet on University Ave. in St. Paul. They knew I was coming and what for. The replacement hose came in a box as thick as a pizza box and about 14 inches square. When I got there the guy pointed me to a stack of pizza boxes as tall as me and instructed me to grab one and sign here.

That 2.5 liter was a great little engine but it sure shook those hard AC lines.

Oh and pretending this is still on topic - I've never seen nor heard of a 4 cylinder in 67-72 GM pickups.