balance installation issue with rod insert

Last year I purchased a pair of your balances after sending a photo. I just got around to installing and the (existing) rod that rests in the metal part of the balance doesn't fit. You can see from the photos there's a ridge on the old rod and the required part should be just a rectangle without the recessed part. Can you help with 2 new rods designed to fit your balance? There are two screws attaching the rod to the base of the window.

Well, we've already successfully installed one 15-105 and broken the existing pivot shoe trying to get it to work with the 15-105. My ideal world would be to get the pivot bar for the 15-105 and be done with it. Turns out the other side doesn't need replacing - although I'll get two pivot bars as I have the other 15-105 here at the ready in case the other side blows. Thanks, Paul - can you let me know the number of the 15-105 compatible pivot bar?