Wiper arm spline replac?

[rideblue00]

I have it already out of the truck. And i am a machinist and a welder, so i do ok on repairing stuff. I was planning on just replacing the spline. I just need to find a source for the knurled pc. Newer van ones are larger in diameter. I was hoping to come up with a easy and cheap repair. Spending money on used ones with out seeing the splines is a crapshoot. And the repros are $80-90. So i need some used ones to experiment with.