If you have to remove the PTO drive shaft, don't get frustrated by sliding it in and out trying to line up the splines. 

Weld a nut on the end of the threaded rod Chris said to use to pull the plug and shaft back. Once the shaft is back to the splines put an impact on the threaded rod and pull back while turning, the jarring effect of the impact will line the splines in an instant! WB&lt;&gt;&lt;.