[lightning1225]

Hi. This is my first post to the forum, and concerns the blade arrangement on a model 441 38" mowing deck, mounted on a 1225 lawn tractor. The deck spindles each have two blades; a 12-3/8" long straight blade, stacked at a right angle above a 19-5/16" long curved mulching blade. I'm replacing the mulching blades with a similar Stens model, and I'd like to know more about the short guys that are apparently part of the original configuration.
There are 5/16" side holes in the main blades that align with holes through the spacers and through a large round center section of the short blades, but there is (currently) no bolt or other means of maintaining any indexing of the short and long blades, thus they can and do migrate somewhat relative to each other in use. What is the purpose of the short blades, and should there be bolts through the side holes to maintain alignment with the new long blades when I install them? The short blades do have sharpened edges. Was this some sort of new magic in 1993?
I'd appreciate anyone's insight into this arrangement. Thanks.