Chevy part number is 590514. Listings show the part as being relevant to 1938 to 1947 transmissions. I'm not a chevy guy so who knows?
A quick google search turns up new old stock examples available for reasonable prices:
ebay:
http://www.ebay.com/itm/NOS-1938-47-...RWZgrp&vxp=mtr
Auto parts website:
http://www.autopartsobsolete.com/193...gm-590514.html