Bob,
On another note for this topic,
this page in the 1929-57 MPL provides more info about the "dowel" that Kevin mentioned in his reply.
That part isn't being reproduced anywhere I could find, but the part description (see snapshot attached below) shows that part is basically a piece of steel round stock with a 3/8" diameter and length of 2-23/32". Something I think could be fabricated to fill the need for this missing part.
Hope this may be of some help?
Dan
