Daytona Races 1968
On a hot day in July, Bobby Isaac cools off under the back of Richard Petty's #43 at the Firecracker 400, Daytona .  Check out the aerodynamic sheetmetal work on the bottom of the car.  Also, Isaac's car to the left is one of the two Chrysler experimental 2 x 2 chassis.  This car later became the #71 Daytona mule at the Chrysler Proving Grounds, and is now the #88 car at the Talladega Museum. 

The 2 x 2 nomenclature refers to inches  and to the way the body was positioned on the chassis.  Since the body was dropped 2 inches in front, they needed to make a special recessed intake for the car, so the hood would  close.  NASCAR figured out something was up, and made Chrysler raise the cars.   In the revised configuration, they did not run well in the race.   Chrysler was told not to bring those cars back.   Chrysler spent a lot of effort on this project, for naught.    Isaac's car is also the car wearing #88 at the Talladega Museum.   Petty's car, however was not one of the 2 x 2 cars, but they had their own massaging tricks they had performed.   
Another shot of Richard's July 1968 Road Runner at Daytona.   This is the car with the white top.   This car was NOT a 2 x 2 car like Isaac's.  One of the other things Chrysler came up with during this period was an aerodynamic wheel with a built in hubcao or fairing, and only a small hole to access the lug nuts.  They tried to sell it to NASCAR as a safety reinforced wheel, but they didn't buy it.  No pics have been discovered of the wheel to date.
Here's a shot of Richard's Daytona 500 car from 1968.   It was taken early in Speedweeks as there is only one contingency decal on the fenders.
A rare color photo of Richard and Al Unser in Cotton Owens' Charger at the 1968 Daytona 500.   Check out that Richard's wheels are painted dark blue.  In most photos they look like black.  They are not.