There are some mobile half wave and some 5/8 wave mobile antennas available, just do a search on the internet. But you're talking an HT antenna? Most duckies are half wave. Are you looking for a gain antenna? There are plenty put there, see all the ham radio supply houses, they all have them. You need to be more specific on your needs.
Clyde, N1BHH, A Know Code Amateur Radio Operator, since 1970
WQLF416 = GMRS
Pro's 94, 106, 164, 197 (2), 2006, 2015, 2021, 2055
Yaesu FT-60R, 2900R, 8000R & 8800R, Motorola MTX9250, Icom IC-735