In picture one the bottom shaft is the IE-1500. Hobb cutter marks are intentionally left fwd of the overdrive section splines.
Pic 2 shows the IE 1500 on the left. We do not insert plug in the end of our shafts the tips are machined/part of the shaft.
Pic 3 shows the IE 1500 on the right. This pic was posted to show that our shaft doesn't press in a governing hole. Instead it is removable and can be done with a 5/32's allen wrench.