manual steering box ID

You need to find out if it's big or small pinion spline. I believe Moparts or Big Block Dart has a tech section. I've read you can tell by looking at the top plate

http://www.forabodiesonly.com/mopar/showthread.php?t=68591

http://www.forabodiesonly.com/mopar/showthread.php?t=98910

http://www.bigblockdart.com/techpages/techindex.shtml

http://www.bigblockdart.com/techpages/steeringbox.shtml