'91 Rear End fit into a '66

Will a rear end from a 1991 5.0 fit into a 1966 FB?  

Anything can be made to fit but one must consider that the 1991 uses coil springs and a different U joint connection.  You will need to cut off the 1991 suspension bits and weld on spring perches and modify your driveshaft.  I don't know about the width of a 1991 axle assembly vs. a 1966.  I suspect the 1991 is wider but you can probably make up for this with wheel offset.  

Try looking for a 1957-59 big car rear endit is a direct swap and you get a 9 inch, most have 2.80-3.00 gear.If you want lower gears try a 1966-1977 ford bronco itis the same flang to flang but you will need to move the spring perh plus you can find detriot lockers in them.also you can swap 77-1980 lincolnVersailles which have disc brakes or 75-1980 ganada/monarchs wich come with bigger drums.  

i mit be wrong on the bronco i'am looking for a swap for my 66 and just fond some carts saying the bronc is 50" flang to flag not 52 like the 66 mustang.