Can I drop a 351 Windsor in my '89 Fleetwood or does it require adaptation.

351 Windsor is a Ford Mo CO engine. Will need a lot of adaption if it has any chance of working. Likely a huge project, if it would even work.

Going to take a lot of work. Are you asking because you have a 351 on hand, or are you just looking to make a GM/Ford hybrid?

Thanks. Scrap that idea

"Unlike the 700R4, the 200-4R has a multicase bellhousing for use with Chevrolet, Buick/Olds/Pontiac (BOP), and Cadillac powerplants. Since the external dimensions are similar to the THM-350, 200-4Rs are often swapped in place of THM-350s in older vehicles to provide an overdrive gear. (However, in situations where case clearance and the need for drive shaft modification isn't an issue, the TH400 is more of a close mounting match to the 200-4R. Placement of the mount is identical. The yoke needs to be changed in most circumstances, and the drive shaft length will be different as well.)"

you should be able to easily swap any sbc easily.

My 305 is 300K old and tired. Want to rebuild an engine with fewer emmisions and a little more juice that will "drop" in fairly easy.

LV2

Oldsmobile used the popular LV2, a 307-cubic-inch (5.0 L) engine, commonly known by the VIN code "Y", from 1980-1990. It was used by every domestic GM automobile marque. Roller lifters, floating piston wrist pins, and swirl port intake runners were added in 1985.

The 307 "Y" produced 148 hp (110 kW) and 250 lb·ft (340 N·m) in 1980-1984 models and 140 hp (100 kW) and 250 lb·ft (340 N·m) in 1985-1990s. All LV2s feature a 4-barrel carburetor.

Y-version applications:

1980–1985 Buick Lesabre
1980–1985 Buick Riviera
1986–1987 Buick Regal
1986–1990 Chevrolet Caprice
1980–1985 Oldsmobile Delta 88
1980–1984 Oldsmobile 98
1980–1985 Oldsmobile Toronado
1980–1990 Oldsmobile Custom Cruiser
1980–1981 Oldsmobile Cutlass
1982–1988 Oldsmobile Cutlass Supreme
1982–1986 Pontiac Parisienne VIN "Y"
1988–1990 Cadillac Brougham VIN "Y"

your car also has the 200r4, which has multiple brand bolt pattern. any chevy 350 will physically bolt in, the problem is hooking up everything else. if you want simple a aftermarket carb and 70'* one wire vac. advance dist will get rid of all the computer stuff. if you want tbi, or lt1, or ls engine its not impossible but would be a little more money for computers and that to get it running.

found this on a caddy forum.
"OK THESE TWO GUYS ARE SCARED OF A LIL CHALLANGE.(JAYOLDSCHOOL,DEVILLE33) I TOOK OUT THE OLDS 307 AND DROPED A CRATE CHEVY 350 IN THERE NO PROBLEM!WITH EDELEBROCK CAM, INTAKE (PREFORMER RPM SERIES), AND CARB (650 CFM MANUAL CHOKE) WITH HEADERS! AND THE 2004R TRANS,TRANS MOUNT, AND DRIVE SHAFT WILL BOLT UP FINE.AND TO MAKE IT EVEN MORE EASY GET RID OF THE TBI SO YOU DONT HAVE TO WORRY ABOUT WIRES.PUT A CARB ON IT, THE ONLY WIRES I HAVE IS ONE 12 VOLT TO HEI DISTRIBUTOR CAP FROM IGENTON(PINK COLOR). FOR THE STARTER ONE FROM BATTERY TO STARTER AND ANOUTHER LIL 1 THAT GOES TO IGENTION .AND FOR THE ALTENATOR (3 WIRE STYLE)CONNECT THE BATTERY TO IT ON THE BACK AND FROM THERE PUT ANOUTHER WIRE TO THE LIL POST MARKED #2. WHAT YOU WILL NEED IS DIFFRENT ENGINE MOTOR MOUNT BRACKETS AND EXHAUST. EASY!! MY 1ST MOTOR SWAP DONE IN ABOUT 3 WEEKS AFTER WORK.

86-89 chevy caprice headers from summit. Slip rite in "

If your gonna spend the time i would go with a 350 0r a 307 chevy not olds...

that info i posted was what he has. you dont want any 307 or 305, chev 350 or any derivative is what you want for power and reliability. most crate engines even the mild street ones have twice the power of what you have and likely will last just as long.

Ok i thought you were reccomending one lol ..I have one sitting on an engine stand...Best place for it..But yes there is a reason 350'* are so popular..Huge aftermarket easy power and cost effective