dwortho,
The original configuration of the blinkers was for the brake lights to flash. If you have a look in the original workshop manual in the Electrical section, you'll see how the wiring block behind the blinker stalk makes it all happen. You'll probably have to adjust the wiring to match the FB ute/van, which had the combination you're looking for. I presume you've connected the rear blinkers to the front blinker circuits, so now you need to remove the blinker can from the original rear circuit. As I said, it all makes sense if you study the Workshop Manual.
You could also compare the two wiring diagrams available in the
Tech Info area.
cheers
RET