Damn good deal!
If anyone is thinking you need anything special to weld exhaust cracks, and that puts you off.
Yes, you Do, if it’s stainless.
These aren’t, so you can weld with standard mig wire. Technically it should be 316, but I’ve done it often enough with mild steel wire.
The steel is coated, so prep with a good wire wheel, or flap disc. I run a cutting disc at slow speed into the crack to get any rust or carbon out. Turn the gas up a little bit, then weld a little, maybe 20%, at the center of the crack. LET THAT FULLY COOL. Weld the rest.
Be aware, there will be spatter!
Give the area several coats of zinc spray, or high temp paint. The repair is good for at least a couple of years.