To suit which size of figures?
Not my period, but as far as I know vehicles weren't something the NVA used in the South until later in the war (1968>?) and then with one or two exceptions, only against the South Vietnamese. Jeeps and trucks were used on the Ho Chi Minh trail and North of the DMZ they had the usual range of T55, PT76, BTR-40 and BTR-152 vehicles in use. I'm not certain about the BTR-50, but the current Vietnamese Army has them, so maybe.