Put benson.dFF and benson.tXD in a folder inside of your modloader folder or remplace the files in your gta3.img...
Remplace the lines in handling.cfg, vehicles.ide and carcols.dat respectively:

Handling:
BENSON       9500.0   57324.6   2.3    0.0 0.0  0.0  60  0.50 0.7  0.46 	4 180.0 18.0 30.0 R D 	8.0   0.45 0 35.0  	1.0  0.06  0.0   0.31 -0.15 0.5  0.3		0.66 0.60 60000 	22001A 		100000 		2  1 	16 

Vehicles line:
499, 	benson, 	benson, 	mtruck, 	BENSON,		BENSON, 	bus,	worker, 	2, 	0,	0,		-1, 1.08, 1.08,		-1

Colors line:
benson,  1,1

(Optional) open cargrp.dat and put "benson" in the following sessions:
# POPCYCLE_GROUP_CASUAL_POOR  
# POPCYCLE_GROUP_SERVANTS

-IonicCleric8076-