I remembered I have a D4 7U27570-UP parts book. The shaft you describe is part# 3B2517 for these machines. My experience with D6 parts is that they do not change much but you can never be sure. A parts machine depends on condition and years difference. Your situation and ability to disassemble for a part may dictate your choice. For some of these parts even my time spent makes it cheaper to buy when I can find the part. Several years ago there would have been salvage yards that could accommodate, but high scrap prices took a lot of these old machines away.