79- 425 flex plate

[Greg 18360]

Does anyone know if the  Seville  and  DeVille  flex plate is interchangeable, 79 model year.
          Thanks Greg

[TJ H 20664]

A 79 Deville most likely had a Cadillac built 425. A 79 Seville should have had an EFI Oldsmobile 350. I know the diesels were an option on the devilles and may have been an option on the seville by that time.  I would assume since the diesel was based on the olds that the bolt pattern for the crank was the same as the olds gas engines.  You also have to pay attention to the torque converter bolt patterns, there are at least 2 common sizes that look the same till you try to bolt them up, they are only like 1/2 inch or so differnt in diameter. As far as I know the Cadillac 472/500/425/368/368 V8-6-4 engine family had its own bolt pattern for the crank that didnt match anything else.  I have been told its close to some older Fords.  There were differnt versions of the flexplate over the years but the crank pattern was always the same as far as I know. There are new flexplates available for the cad motors that have both sets of torque converter bolt holes.  Bellhousings are all the same after 68 for the Cadillacs and Buick-Olds-Pontiac sometimes known as BOP so you can use THM400,350,200metric, and the 200r4 (or 4r i cant remember).  Sadly there was never a 700 made for anything other than chevs.

Are you thinking of putting a 425 in your seville?

TJ H
20664
StPaul/Mpls MN USA
73 Eldo convert(s)
78 CDV