ok, so I got an older car and bought all new speakers n stuff and it uses the basic 6x9 in the back and 3.5 inch in the front and Im thinking of getting a ford ranger which has somewhat smaller speakers than 6x9 in the back and in the front is the same, somewhat bigger than 3.5 in the front. would it be possible to convert the hole sizes for them or do I have to buy all new speakers for it?