Bob: my S-10 shaft is 7-1/8" give or take a hair. Measured to front of the case and not bearing retainer.
Stock front bearing plate is a weak point in this trans and cutting it down reduces support for bearing. If you do this get one of the aftermarket steel retainers that offer more front bearing support.
http://www.fordmuscle.com/archives/2000/02/t5/index2.shtml
