Is there a way in the VIN to tell if an 05 mustang is either a manual or an automatic?

 

No, there's not. Have to look on the door tag
This is the VIN decoder from Ford: 2005 Ford Mustang VIN

Here's my VIN broken down.
1st, 2nd, & 3rd: 1ZV = Vehicle Manufacturer: Automotive Alliance International (USA)
(NOTE: Not Ford. All the other codes are Ford Motor Company)

4th: F = Restraint System: Active belts, Driver and passenger air bags

5th: T = Passenger Car Identifier: All passenger cars imported from outside North America or non-Ford built passenger cars marketed by Ford.
(NOTE: Must be why the ERL always said our cars were "Released from foreign assembly plant..." Obviously the Mustang gets this code because it's built at a Mazda plant)

6th: 8 = Line: Mustang

7th: 2 = Body Type: 2 door coupe

8th: H = Engine Type: 4.6L 3V OHC

9th: 3 = VIN Check digit: No clue on this one!??

10th: 5 = Model Year: 2005

11th: 5 = Vehicle Assembly Plant: AAI, Flat Rock, MI
(NOTE: AAI's the only one with a number here. All other Ford's have a letter. Must be a Mazda thing.)

12th-17th: 173361: Sequential Vehicle Identifier


From the looks of it, we really do have the Mazda Mustang that Ford predicted oh so many years ago.