Got an 85 Ford LTD Country Squire with the 5.0 cfi. Not my first squire nor my first 302, but this sound is a first. It’s all stock, no rigged up junk. When cranked from cold, and left to warm up slowly, a clunk/pop comes from the engine area. The engine doesn’t miss a beat. No smoke, or fluids going crazy. To me it sounds like metal expanding, but to my knowledge I’ve never heard this on a cold engine. I feel silly for asking, as a hot engine cooling down makes racket, but I guess I’m being over protective of this wagon. thanks everyone!!