You can fit a manual transmission into an automatic Ford Mustang as long as you have the same engine but you will have to change a lot of things. Depending on the year, you would have to change things like the computer, wiring , steering column to add the clutch, etc. It would be better to buy one that's a 5 speed already.
Both automatic and manual transmissions are offered on most of the Ford Mustang models
No , just the automatic transmission has a torque converter
The 1987 Ford Mustang came with a T-5 five-speed manual or optional automatic transmission.
Motorcraft MERCON automatic transmission fluid for your manual transmission
look in the manual
Manual: TR3650 Automatic: 5R55S
The 1989 Ford Mustang GT came with a T-5 five-speed manual or an optional automatic transmission
Motorcraft MERCON automatic transmission fluid in the 5 speed manual transmission according to the 1997 Ford Mustang Owner Guide
You are going to have to get a new car
According to the 2002 Ford Mustang Owner Guide : 3.8 liter manual transmission fluid ( Motorcraft MERCON automatic transmission fluid ) 4.6 liter manual transmission fluid ( Motorcraft synthetic MERCON automatic transmission fluid )
On a 2005 Ford Mustang GT the automatic transmission does not have an automatic transmission fluid level dipstick ( and the manual transmission fluid level is checked underneath the vehicle at the transmission fill plug )
According to the 2003 Ford Mustang Owner Guide : 4.6 liter manual transmission ( MERCON automatic transmission fluid )