You need a 1234485 rear bracket which is the same as 350-455 A-body. 1234487 Front bracket which is also the same as 350-455 A-body. You also need a 1237440 rear brace which is unique to your needs. You can see a picture of this if you have an assembly manual ('72 Full Line) for big cars page 9-3.1
Big cars have this stamped on the parts: BCE which believe refers to the Fisher Body designations B body, C body and E body. Skylark/GS is A body. Have these parts from 455 powered '73 Electras.
Matt, Thanks for the info.My assembly manual is buried in a storage unit.I apparently have been running with the wrong setup for over 20 years.Needed to replace ps pump and it will not fit on existing brackets..The only stampings on existing brackets say 350 231 that I am sure is not correct for my application.
The 350" PS for the big cars is a separate drawing. 350" also uses a different shape pump housing. Happy to help.
MK may have the right info. Aluminum and stamped steel bracket seen in earlier post may? have come from a '70 large car engine I stripped front brackets from. PS pump and it's front stamped bracket, are definitely from a pair of '73 Electras that was able to scavenge a few bits from. First pic: 455 engine with '70 date code. Second pic: '73 PS pump with attendant steel front mount bracket. 455 car. Third pic: Believe A/C brackets and bits from '71 - '76 large cars with 455 engine. Don't believe all, or possibly any BCE P/S brackets crossed over during the '70 to '71 redesign.
Why did Buick use different brackets for A and BCE cars? Seems like there must have been good reason to spend money on tooling and carrying two sets of parts. I've been curious. Anyway Nick, at least bumping your thread with my question!