It seems like the pickups had a lower MPH top end like 80 MPH while the cars had the 100 MPH. These were originally silk screened. There should be someone out there that can re-screen it for you. If there is a difference on MPH between the car & pickup your speed indications would likely be off unless they make a decal to match the one you have. This is one of the fun parts about the resto hobby.
Kerby