Help Valuing Yamaha YFB822 vs 821

[bstevens]

Hi

I've got an Yamaha YFB822S that I bought in 2013, but is from probably 90's era as pre-custom stamp. Plays very well. Condition is decent - no dents but some silver flaking and some scratches etc.
I have the opportunity to swap it for an YFB821S plus add cash. I think from 2018 or so - good condition all round - not brand new, but no dents really or many issues on any of the valves or silver finish.

Any ideas on the value on either horn? I know it's tricky without photos but any thoughts welcome. I have a rough idea but just want to check I'm not kidding myself.

Thanks, B