sorry for the stupid question but i know nothing about manual trans. how do i identify a sm456? Thanks

If you mean a 465 trans they have a PTO cover on both sides

From the Novak website:
http://www.novak-adapt.com/images/pics/sm465_flq_lr.jpg
http://www.novak-adapt.com/images/pics/465_shaft_array.jpg
Identification
The SM465 has a case length of 12". It is also identifiable by its large, 5-1/8" diameter input bearing retainer. The case itself is generously ribbed both vertically and horizontally. There are three different versions of this transmission - the differences lying mainly in the output end of the main shaft. The early four-wheel-drive version (picture, uppermost), from 1968 to 1979, has a 10 spline involute output shaft that sticks out 2-5/8" from the rear face of the transmission case. The second variety is the two-wheel-drive style (picture, center) that has a 35 spline output shaft with a threaded end. This version spanned the entire production period of the SM465. The later four-wheel-drive version, 1980-on, main shaft (picture, lowermost) is the longest, has 32 splines