That first
Unit is just as I thought, the old three wire Chromalox, the extra wire is a ground, these have seven heat switches and change heat settings by sending different voltages..120 or 240 thru all or different coils , the bake unit should also be fairly easy to re string, you buy the nichrome heating element wire and pull it thru the insulators, also, you can replace the old style bake unit with a modern rod type used in newer ranges, this would probably be your best bet, start going to old appliance/furniture stores, and thake those elements with you, seeing is always better than giving model numbers to someone who may have never seen a range that old.