It depends on which engine you have in the 1970 Challenger. If you had the 318ci, you could expect to get 11 - 14 mpg. With the 426ci hemi or the 440ci six pack, you could expect 6 - 10 mpg,...
There are 2 adjustment screws on each light that align the headlight, one will raise and lower the light and the other will move the light from side to side.