Instructions: place the DFF, TXD and FXT files along with this text file into the modloader folder. In case you don't use modloader you can do the traditional installation, replacing the forementioned vehicle files, the TXD and DFF in the GTA3.img and place the following data lines in their respective game files from the DATA folder

Handling.cfg
BUFFALO 1500 2400 2.0 0.0 0.0 -0.1 80 0.70 0.80 0.5 5 200 28.0 10.0 R P 6.0 0.50 0 35.0 1.0 0.07 5.0 0.25 -0.10 0.45 0.0 0.38 0.40 15000 C0002000 00000002 1 0 0

carcols.dat
car4
buffalo, 87,87,0,0, 1,1,0,0, 105,0,0,0, 3,3,0,0, 65,65,65,0, 0,0,0,0, 79,92,79,0, 25,25,25,0
end

vehicles.ide
402, buffalo, buffalo, car, BUFFALO, BUFFALO, null, executive, 5, 0, 1f10, -1, 0.67, 0.67, 0

carmods.dat
buffalo, nto_b_l, nto_b_s, nto_b_tw, spl_b_mab_m, spl_b_bbb_m, spl_b_bab_m