Grind/rattle noises

Hi guys
2013 Jimny
Getting some strange grinding/rattling noises but only when everything hot say after 5 or 6 miles. Mostly happens changing up from 1st to 2nd and sometimes 3rd. Mainly around the 20mph range. Also get some rattling type noise when taking foot off the gas, again at the 20 mark.
Have had oil levels in boxes checked as ok and intend to change them next week with fresh.
Cant see anything obvious loose underneath. Gear changes feel smooth and no loose or tightness on clutch
Bit worrying these noises. Any ideas welcome

Hi, I had a strange rattling noise, when putting in gear (automatic) when cold. This was has been said by Lambert, the catalyst heat shield. One bolt completely rusted away. My rattle goes when he’s hot!

Worth checking as an easy fix.

Pete

More the former. Deffo no knocking
Ive had a quick grab of most things underneath and nothing seems loose etc. Will look further tomorrow though when its hot.
Cheers for the suggestion

Update
Looks like all heat shields etc are solid so not coming from there.
Stuck a camera underneath after first driving 12.5 miles to get noise to start again.
2nd gear mostly, foot off gas at 20mph noise starts
Have vid with sound but cant upload here for some reason. Im guessing because its in mp4 format?

check the 4wd drive locking front hubs, it's possible they could be ever so slightly catching when they either warm a tad or experience pressure from either a left or right hand bend

certainly worth a look, can sounds like a machine gun type rattle when they catch