My 1973tii came with a 3.64 rear end stock.
This from another thread:
3.45:1 diff -- W=1.24 speedo
3.64:1 diff -- W=1.297 speedo (W=1.30 is close enough)
3.90:1 diff -- W=1.39 speedo ('76 49-State 2002)
3.91:1 diff -- W=1.393 speedo (E21 320is LSD)
4.10:1 diff -- W=1.4 speedo (1.461 calculated)
4.11:1 diff -- W=1.4 speedo (1.465 calculated)
4.38:1 diff -- W=1.559 speedo (calculated)
http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/p,656384/highlight,speedometer/#656384