macomber-v-beam steel joists

huangyhg

macomber-v-beam steel joists
we recently completed an inspection of a structure constructed in 1969 that is in need of renovation, and have the tags of all the installed joists, which are designated "macomber-v-beam".  among other information on the tags, the id numbers on some of the tags are as follows:
28e 40 0 u
18d 25 0 2g
28j 39 0 d
28g 39 4 m
28h 41 8 b
it appears that the first three digits identify the joists (nominal depth and family), the next three numbers represent the joist span in feet and inches, respectively (makes sense based on field dimensions).  however, i'm not sure what the last letter represents.
i know this might be asking a lot, but could someone provide me with any information regarding this designation?
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i believe mattman has this info - he haunts the site occasionally - or do a search for macomber in eng-tips to find out more...this has been discussed in the past.
isn't there anyone who used to work at macomber or some old-timer (sorry, mattman) who has some files that they could make available?  this isn't ancient history.  it seems we get more questions on this product than all other systems combined.  it must of been pretty popular in its day.  maybe the files could be contributed to the steel joist institute and they could make them available on their website.
another possibility is that macomber was absorbed by someone else and the records are gathering dust somewhere.  i did an internet search, but only got hits here.