Pictures and Descriptions of the B.O.P. 9778882 (882) bellhousing

The Buick,Oldsmobile,Pontiac "882" is an all aluminum Bellhousing.
These clutch and flywheel assembly covers were manufactured for multiple applications,
as evidenced by two starter housings and dual transmission mounting bolt patterns.
In 1965 General Motors used Dearborn built (Ford) 3 speeds as a heavy duty option to the Muncie 3 and 4 speed trans on some models.
Instead of casting different bells they made these more universal.

Front View
Here you can see the two trans mounting bolt patterns.
Four holes tapped 7/16"-14 for the optional Ford 3 speed trannys and four tapped 1/2"-12 for the GM production trannys.

Part #
The part number is cast into the drivers side starter "ear".

Top View
This picture shows the "V" in the engine mating flange and is indicative of a B.O.P bell.

Fork side

Bottom
These bells utilize a one piece sheet metal inspection cover that wraps around from engine side to bottom,
and is attached by three 1/4"-20 bolts.

Drivers Side View

Engine side view
In this picture you can see the two starter "ears" and the engine mounting flange,
with six clearance holes for bolts and two dowel holes.

Inside view
This angle reveals the fork mounting stud location and beefy reinforcements around all mounting holes.

Factory correct applications are your responsibility. Gm made part and part # changes with no rhyme but a reason(no production interruptions at any cost).
My observations come from the parts I have in my collection or other reliable sources your parts may differ.
If Factory correctness is your goal,do more research,join car clubs,forums and buy an assembly manual if one is available for your Project Car (you wont be sorry). This is a fun and interesting part of the hobby!