Replacement flasher for high current draw

I think you need a solid state replacement for your factory mechanical flasher control unit.
Maybe try one out, see if your system can bear the load. Need clean and good connectors and wiring from the battery, front of car to the tail lights.

http://www.wiringproducts.com/contents/en-us/d140_automotive_flashers.html

two variants of electro-mechanical replacement flashers on this page..

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What parts are required to make the wrong part functional is moot. A 1157 bulb has a 32 cp bright and a 3 cp dim filament. A halogen 1157 is 50 cp bright and 15 cp dim. So instead of approximately a 10-1 ratio you have about a 3-1 ratio. It will be hard to tell the difference between running lamps and brake lamps at night.