Anaheim Foundry offer a reproduction of the Chevy "621" bellhousing.
They say:
Improve the performance of your Chevy transmission with Chevrolet bellhousing from our experts in Yorba Linda, California.
Our high-quality reproduction of the Chevy "621" bellhousing is good to use with all big- or small-block Chevy V-8 motors, including 409s.
Anaheim Foundry
17052 Rancho Lane
Yorba Linda, CA 92886-3202
Phone: 714-501-6118