We have worked with the people at Penske to come up with the ultimate shock for the early vintage race Mustangs. This is a single adjustable aluminum bodied gas shock with no external reservoir. These shocks can be adjusted externally and can be rebuilt or custom valved for each specific application. The nitrogen charge can be checked with a special gauge available separately. Minor spring rate changes can be made by increasing or decreasing the pressure. These will bolt in with the use of coil-over style rear spring plates, available separately. We have found more stability at any speed with these shocks while greatly reducing lap times.