Excellent Condition Refurbished TH400 BCOP, BOP 2WD heavy duty case empty ,Tag 70-AA-176185 General Motor Corporations:
Buick , Cadillac , Oldsmobile , Pontiac .This particular case takes a 8 bolt pump 
 
The following information will center around the most commonly encountered engine mounting flange configurations which are separated into two groups. The first group is comprised of transmission cases designed to fit Buick, Cadillac, Oldsmobile and Pontiac engines and is referred to as the BCOP casting. 
 
All 1965 thru 1974 transmission cases were cast and machined to accept the eight-bolt oil pump assembly. The heavy duty BCOP case include several casting benefits that significantly increase the structural rigidity of the component. Note the reinforced bellhousing area of the heavy-duty casting with its increased material in the bellhousing mounting area and cast reinforcement ribs.
 
Heavy duty BCOP cases were cast with a significantly thicker oil pan mounting flange. 
 
Heavy duty BCOP cases were also cast with additional reinforcement ribs/webbing which extends from the rear of the valve body mounting flange to the oil pan mounting flange.  The reinforcement ribs are also found on all Bentley, Jaguar, and Rolls Royce issue TH400 cases.
 
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