I've got one extra SealSkin Smock in size M/52.
 
Going cheap :) This is a customer return, but is basically new.
 
I've got some information about the sleeve length of these here:
Sleeve length measured in a straight line from the center of the back at the neckline to the bottom of the sleeve:
size 48 - 84 cm
size 50 - 86 cm
size 52 - 88 cm
 
 
More information about it here on the manufactures website.