You've selected the flat pitman arm reamed to a GM tie rod taper 5-5/8" from center of spline hole to center of tapered hole.

This is a flat FORGED pitman arm (no drop).  It comes tapered from the bottom up for a GM tie rod end (example part numbers:  ES2234R, ES2233L, ES2010L&R) at 5-5/8".  Typically used with a 6" steering arm (center of ball joint to drag link hole) for lock to lock steering. 

WARNING:  If you're cutting off the excess material, you must leave 1/2" material around the around the big side of the tapered hole.

Made to fit a Saginaw 32 spline power box spline (no master/key way splines) which allows you to adjust steering wheel center as needed (no need to file the flats because it doesn't have any).

Specifications

• Overall length (tip to tip):  8-3/4"
• Drop:  none
• Center to center length (sector shaft to drag link hole):  5-5/8" C-C for GM tie rod taper
• Sector shaft hole:  32 spline Saginaw power steering
• Sector Shaft Hole, (Small Side 1.18", Large 1.22")
• Drag link hole:  GM tie rod taper (fits:  ES2234R, ES2233L, ES2010L&R)
• Drag Link End Tapered Hole (Small End .659")

CA Residents: Prop 65 Warning