some small differences in the casting
rear support stops before base on left model and rear support continues to base on right. larger angle brace on left model.
http://img391.imageshack.us/img391/5199/boattrailerrear1oi5.jpg
larger inner and rear angle braces on left model
http://img232.imageshack.us/img232/6286/boattrailerrear2vx2.jpg
different supports above lesney
http://img503.imageshack.us/img503/5477/boattrailerrear3pq5.jpg