Loud rattle on return to idle?

[Kickinthetires]

1963 Series IIA. Last night I removed, cleaned and replaced the oil pan/gasket and the oil air cleaner/hose. I filled everything with oil and started the truck - perfect - and let it idle for about 5 minutes. Before shutting it off, I revved the engine and held it at 2,000rpm and it sounded great. When I took my foot off of the gas and the rpms dropped to idle, it made a loud rattling noise as the revs dropped. I revved it up again with no issue, and a loud rattle when I took my foot off the gas. Not sure where to even look! I only touched the oil pan and the oil bath air cleaner.

Any ideas on what to check? Thanks.....

[cedryck]

Any loose bolts on oil pan?

[Kickinthetires]

No loose oil pan bolts. I did have a friend/pro mechanic listen to it and he said it definitely is not in the engine and it is a vibration somewhere...so at least I can start trying to wiggle different parts to see if I can find a loose one. It seems to only make the noise around 1,500rpms.....

[80sailor]

Not sure if this helps, but every time I open the dash panel I find I get a different rattle. Or an old one goes away. Seems that at certain RPM's (usually lower) a wire will rattle against the metal plating inside there. I've just tried to get used to it, but man it's frustrating to try and fix.

[cedryck]

I had a rattle, is was one of the turnbuckles that attach the cover for the seat box. I have under the seat military tanks. Made a loud noise at about 45 mph. Drove me crazy till I put my hand on it and discovered it,,