Trying to identify plastic window top guide lock

Window is an old aluminum single hung window with spiral balances. However the top guides of the sliding portion of the window are broken and need to be replaced. They are screwed in on the top and on the side with a plastic tab-latch which locks the top part of the window into the frame and allows the window to slide up and down without falling out. The tab-latch portion of the guide is broken.
Can someone help identify the part? Thanks