Bellhousing information please.

I'm going to look at a bellhousing and need some information.

I know it is aluminum and was last used in a 68 chevelle but I don't know the casting number and if it is original to the car.

I'm going to use it in a future BB-Muncie-Chevelle project.

Two are listed in the Tech Reference article on converting to a 4 speed. The small diameter bellhousing is part number 3858403. The large diameter bellhousing is part number 3899621. I'm assuming these numbers are stamped on the housing.

Are these the only aluminum bellhousings used in Chevelles?

Any other useful information I should know before buying?

Thanks for any help!