Went how I figured. Both stock. 670 has gill muffler mod both sides. 61 muffler has a inner baffle and notta done.
I don’t want to cut on 61 muffler being I am going to sell it.
6.5's J to mid 8's H.
They all would get the job done. Not a race cutting firewood.
12x13 round used, one on top