4
One
Two
Yes.
Yes, they are identical
For a 1991 Ford Crown Victoria : " regular " unleaded , 87 octane
Walk outside, get down and look under the vehicle and count them.
In the gas tank.
Yes, both model years are AOD transmissions.
According to my Chilton's book : For a 1991 Ford Crown Victoria ( 5.0 / 302 and 5.8 / 351 ) With engine oil filter change ( 5.0 U.S. quarts )
On my 1991 Ford Eplorer v6, both pipes coming off the exhaust manifold join together then behind that there seems to be two catalytic converters inline one after the other.
10 degrees advance
Often in the owners manual is where i found the one for my 1991 Crown vic. Hope you have your manual?