This is the 2 pc style for the 6 cyl 3 spd.
The part number of the lower pc is GM 3714477. I got one from gmpartsdirect.com The price was $7.65 but the shipping is expensive. I'm not sure about the part number for the flat upper pc. I bought that on ebay.
On mine, the bell housing doesn't go all the way around as it does for the one pc covers. This is the style that needs to the 2pc cover:
