Have searched the internet and can not come up with a thing on the Bill of Material 27013 2X. Can not read the Year on the Date on this axle. This is not the only Dana with 27013 2X 2X we have and this one has a date of 7 July of 1970. The BOM is one number less than all the rest that were put in a Vehicle by Chrysler. Looking at any Performance Book by Chrysler I have not come across this number but could be in a Hustle Stuff Book but I do not have any. I have come across three of these rear ends and all seem to be E Bodies with vast different Dates on them. Both the ones we have do have performance gears in them, 538, 513, and both have the Power Lock in them. The other that was posted on moparts a while ago has the Track Lock in it and 410 I believe. The ones we have likely have had a gear change by a previous owner but who know for sure.