Alternator wiring differences

[68basket]

I am putting a 5.3 4l60e from a 2005 in my 68. I got the harness from PSI and the alternator is the original from the 2005. The psi alternator connector is 4 pin and only has 1 wire going to it. My alternator is only a 2 pin and has 2 wires going to it. I found in the wiring diagram for a 2005 that it looks like the alternator is duty cycle controlled. Do I just need to buy an alternator for an earlier truck? or try to rewire what I have some way? Thanks for all the info on the site.