I believe your vertical movie pan cel of Sanzo is 
a hand-painted reproduction cel, not a post-
production cel. I don't think Saiyuki is on 
Rilezu's post-production cel list. Also, post-
production cels are basically like any other 
production cels, but are only produced after the 
anime is done. So they're limited to one copy per 
cel whereas reproduction cels definitely have 
more than one copy per cel. (I'm definitely sure 
that I've seen more copies of this reproduction 
pan cel in various online shop...)