Source for the following information: Mustang Red Book.
Ford and the A.O. Smith Company facility in Livonia, Michigan now had control of the production of the Shelby Mustang as it rolled into 1968 with the introduction of a new body style-the convertible which was available in either a GT350 or GT500. To be official, the 1968 cars were renamed Shelby Mustang Cobra GT350/GT500/GT500KR, reflecting Ford's recent use of the Cobra name in all of its performance vehicles and parts.
The nose for the '68 Shelby was restyled, as it continued to resemeble the Ford Mustang with a more aggressive look. The front end treatment was again made of fiberglass and the grille opening carried either Lucas or Marchal foglamps. The hood now used twin front hood scoops along with a set of rear hood louvers.
New Cobra emblems were added onto the front fenders and on the passenger side of the dash panel. The Deluxe Mustang interior was once again used in the Shelby, available in either black or saddle, but the Shelby used a console which housed two Stewart Warner gauges-oil pressure and amps. The storage compartment of the console had a Cobra embossed top. All Shelbys came with the inertia-reel harnesses with the exception of the convertible which used a unique padded bar.
Standard wheels on the Shelby were steel with a mag style wheel cover. Optional wheels were the ten-spoke Shelby wheels which were cast differently than on the '67 versions and have a ball joint interference if installed on a '67.
The GT350 lost some of its edge when the high performance 289 was replaced with the factory 302 V-8 using an aluminum Cobra intake manifold and Holley 600 cfm carburetor. The 302 found in the GT350 is rated at 250hp. Also found on the 302 is a Cobra oval air cleaner and Cobra valve covers. Functional Ram Air was an option on the GT350's, as was the Paxton Supercharger. Additional fuel pressure and boost gauges were mounted on the console.
The 428ci Police Interceptor V-8 rated at 360hp could again be found in the GT500's, this time only coming with a single 715 cfm Holley carburetor which was mounted on an aluminum manifold. Only a few GT500's carry the 427 Low Riser engine which was only available with an automatic transmission. The letter "W" must be on the VIN for an original factory installed 427.
When the 428 Cobra Jet engine became available in '68, the GT500KR replaced the GT500. It put out 400hp although it received a rating of 335hp. The GT500KR carried the same features found on the 1968½ Cobra Jet Mustang. The KRs came with Cobra Jet emblems on the fenders, dash, and gas cap lid.All of them had functional Ram Air which meant for no Cobra oval aircleaner.
Vehicle Identification Numbers - Shelby 8 - Last digit of model year
T - Assembly plant (T-Metuchen)
02 - Body code (02-fastback, 03-convertible)
J - Engine code (J-302, S-428, R-428CJ-R)
000001 - Consecutive unit number
0001 - Consecutive Shelby production number, 00001 to 04450
Stamped on plate which is pop-riveted on driver's side inner front fender panel over Ford VIN.
Vehicle Identification Numbers - Ford Exactly the same as the Shelby VIN but without the consecutive Shelby production number.