Doug and All: It would certainly seem to have something to do with the change to the Bendix design brakes in 1963. I would try to stay with the master cylinder as designed by Chrysler for the Total Contact design. There are many sources that will sleeve your original. 300ly, Gil In a message dated 12/18/2007 12:09:00 PM Eastern Standard Time, 2HsandaHeritage@xxxxxxxxxxx writes: Hi group, According to my parts interchange book, 1963 thru 1965 master cylinders do not interchange with 1962 cylinders. The 1962 unit has a 1-1/8" bore, and the 1963/64 unit has a 1" bore. Is there any reason that the 63/64 units will not work on my H? Thanks in advance, Doug **************************************See AOL's top rated recipes (http://food.aol.com/top-rated-recipes?NCID=aoltop00030000000004) [Non-text portions of this message have been removed] To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: mailto:Chrysler300-digest@xxxxxxxxxxxxxxx mailto:Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/