These are $6 bucks from Amazon.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I have LED's in Otis my avatar and my 40 coupe, the 40 coupe was the learning curve I tried every flasher made for LED's and nothing worked.
I finally broke down and got a hold of one of my sons high school buddy's who became an Electrical Engineer.....he sent me this said throw all those flashers in the sh*tcan and install these.
Everything worked perfectly after I put these in, no regrets....you could have other problems but it sounds like you've covered your bases.