[Elecraft] K3 and Centurion connection?

[H. Cary III]

I've just gotten a like new TenTec Centurion to replace my Heathkit SB-200. I operate 95% SSB and am a bit perplexed about the connection from the K3 to the Centurion.  Yes, RF from K3 goes to RF In, that I know; the question is does the Key Out go to the PTT/VOX or Key In.  I'm thinking PTT/VOX but I don't want to assume and screw this up!  Anyone have this set up that can help? TenTec offices are closed at the moment or I'd call them.
BTW, if anyone is interested in an SB-200 in good working condition, please contact me off list.
Thanks and 73,
"H" Cary, K4TM  K3-100 #3491