I have a 1970 FJ40 with a lift kit. It is a hfs kit with leaf springs and shocks. It must be an old kit since the hfs shocks were made in america. I couldn't find a model number but The rear shocks have on the shock 5251 c220y2. the front shocks have 5247 c175y3. I am looking to replace the shocks but I need to know the correct size Bilstein shocks to use. By the shock size can that determine the lift size? 2 " or 4". I am running 31 x 10 tires.