20-Though paperboard backing can be purchased from most VW suppliers (part # 111-881-795B for '65-'72; 111-881-795A for '56-'64; and 371-881-795A for '73-'79), it is easy to cut out of the boxes that your interior came in. Simply trace a pattern based on the old cardboard inserts. We held ours in place with packing tape. We didn't pat ourselves on the back too much, as we only saved eight bucks--a small percentage of what this whole interior costs.