I never noticed before but the blue base at the top of the page has a larger rear discharge flap like the later brown base.I will check some more blue bases ,the one I have is a shorter flap .
Don't know any differences in catcher dimensions,the catcher I have is the brown catcher and it fits both mowers,it looks darker in the images.
I found a high arch Sunbeam under a mower pile looks like the same cowl.
