Is it a manual trans car or a Fluid Drive? If manual, there are, no doubt, several Plymouth and Dodge flywheels that will work. Not necessary to locate specifically a '49 DeSoto' flywheel. Ray
What is the 'need'? All pre-62 flywheels, L4, L6, (some) L8 and V8 have the same mounting configuration with a variety of 4-6-or 8 attaching bolts. The Plymouth, US models 201-208-218, have a different crank flange position so that flywheel is 'special' and can be problematic on other engines. There is also the choice of 146 and 172 tooth ring gears. New, truck weight, flywheels are available from Vintage Power Wagons and used flywheels are everywhere. With a flange adapter, you can even use a 130 tooth 426Hemi flywheel. .
I just need a replacement because when I try to turn the car on it would make a loud scratching noise and plus the some teeth are chipped from the flywheel
You can have a machine shop flip the ring gear. This exposes the unworn portion of the ring gear teeth to the starter gear. I did mine 40 k miles ago and never had an issue. Some will say that the teeth when flipped lach a beveled approach but it never became a concern.