either make a red texture for these parts or add those missing acc_list to your first .ovr such as the default skin in this addon
SiiNunit
{
simple_paint_job_data : .ovr1
{
paint_job_mask: "/vehicle/truck/upgrade/paintjob/tandem_kast/default_paint/ekeri_box_skin.tobj"
acc_list[]: "kuzov.ekeri_box4"
acc_list[]: "kuzov.ekeri_box4_4"
acc_list[]: "kuzov.ekeri_box4s"
acc_list[]: "kuzov.ekeri_box44s"
acc_list[]: "body_frame.ekeri_4"
acc_list[]: "body_frame.ekeri_4_4"
acc_list[]: "body_frame.ekeri_4_s"
acc_list[]: "body_frame.ekeri_4_4_s"
}