I have a 94 Buick LeSabre that has a powertrain with 97k miles on it, the subframe on the car is completely rusted out and I have not found a 92-94 Bonneville to put the powertrain in. I found a nice 96 Bonneville that needs an engine, but low mileage Series II engines are a bit pricey in my area so I would like to know what all would need to be done to put my engine and tranny into the 96 Bonneville.

Odd....most go the other way around

It could be done, but it is not plug-and-play. The engine harness will have to be completely redone from scratch as there were no factory offerings for the OBD2 computer AND a Series 1 motor. Even then, the PCM will need to be reflashed to effectively run the S1...fuel, spark, knock, and trans tables would be vastly different. And NOBODY has those custom tables yet...except for me, and even those are experimental at best.

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2005 GXP - White Gold Pearl, no mods...yet.
2000 SSEi - Resurrection in progress. Built L67 w/L32 fuel rail, ported heads, and cam. Camaro front brake system, GXP cluster, and much more in planning.

Swap the entire engine, trans, wiring harness, PCM, and axles. You'll need the factory manuals for both cars.

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However, VATS will still need to be dealt with. The truth is, no matter which direction you go, there is going to be alot of work involved. I'm not saying it can't be done, because I know it CAN be done. But, you have to consider the fact that you will be spending a good double or even triple the time in modifying the electrical system to accept the older drivetrain than you would if all you were doing was just swapping the engine with a new, proper powerplant.

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2005 GXP - White Gold Pearl, no mods...yet.
2000 SSEi - Resurrection in progress. Built L67 w/L32 fuel rail, ported heads, and cam. Camaro front brake system, GXP cluster, and much more in planning.

Thanks for the replys. I have had a few replys from guys that have engines for sale, one is a S2 out of a Grand Prix, the other is a S2 engine and trans out of a super charged 96 Bonneville. As far as the S2 out of the Grand Prix which years would be a simple swap?What all would need to be done to swap the powertrain from super charged 96 Bonneville?

The engines would be going into a non supercharged 96 Bonneville.

The swap from a non supercharged series II to a supercharged series II requires the entire motor, pcm, and harness. For the highest probablility of success, take the entire driveline (engine, transmission, cradle, and wiring) from the donor vehicle and install it in the car as a unit. There are internal differences in supercharged series II motors that you would want, so it's more than just taking the top end. By the same token, the PCM is set up for the transmission's gear ratios, so it is best to treat the entire engine & transmission as a unit to be installed together.

From a mere "bolt it up" perspective. Any of the 3800 motors will fit if you are willing to track down all the parts (accessory drives, wiring harnesses, etc.)

Best way to do this: Find your donor car with the supercharged, series II L67 motor. Take all of it, including the cradle, transmission, etc. Get a service manual from the car the motor came from (mostly for the wiring diagrams.) It's better for you if the donor car was another H-body like your Bonneville...as there are differences in the mounting brackets in other platforms. If the donor is a different platform, then someone like Ed Morad can usually come up with the brackets you'll need to get the motor in the H-body properly. The rest is wiring..making sure all the body harness wiring is pinned to the L67 PCM in the proper connector and pin. From that point forward, you car has a split personallity: Any problems with the chassis, treat it like the car it is. Any problems with the driveline, treat it like the donor vehicle the powertrain came from.

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Bye Bye 1990 Bonneville LE... Now it belongs to my daughter
In the Garage: 2009 Subaru Outback, 1987 Camaro, 2006 SV650S, 1995 Regal 182 "ASANAGI", 1962 Ford Galaxie 500, 1995 Ford F150 XL 4WD, 1953 Farmall Cub

Moved to 92-99.

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2012 Ford Fusion SEL, 2012 Chrysler Town & Country, 2007 Chevy Silverado LT, 1999 Pontiac Firehawk, 1979 Pontiac Trans Am