I might be wrong, but I thought that the 2wd PU's had a pitman arm with a tapered hole.
http://www.pirate4x4.com/forum/showthread.php?t=369296&highlight=2wd%2A+pitman+arm%2A(From DWT on Pirate4x4.com) Heres the difference. The arrow points to the master spline that the 2wd arms have that the 4x one lacks. You'd need to file/grind 2 splines off to use it and put a spacer between the nut and arm to make up the thickness difference. Otherwise its about a 3/4" less drop and about 3/4" shorter too.
The arm in the pic I posted came off a 90 2x with power steering.