I had the left one on my stock 2004 fall out (slowly) while I was driving during our latest cold blast.Fortunately it came off slow enough from the big globs of what appeared to be black silicone so I could hang onto it by hand out the window until I stopped moving and could get a large rubber band at where I travelled to to hold it in until I got home to glue it back in.
The glass appears to be a same two sided piece of mirror in that odd housing shape so that is reversible to fit the passenger side also,if reversed and glued in there.It is thin..say 1/8" thick.
I glued mine in with more of the same big globs of black silicone and used clamps to hold it in place until the stuff dried.
It seems to be holding okay.You may be able to find a match at the JY. If the one side that fell off isn't available..check for one from the other side of the donor van,,since they appear to be reversible with mirrors on both sides.The black silicone on the back came off easy with a razor blade and didn't leave any marks,so it would have worked again for either side as a replacement,just reversed to fit the odd shape of the mirror/glass portion.
I don't know if the year models changed glass or shape of the housing..I'm only assuming they are the same..Is there something better?In the PNW we don't get the radical cold spells(or only for a few days),so it doesn't seem to be much of a problem here.