I purchased a new oil pan off of e-bay for my 66 Mustang. It said it was the stock oil pan for Mustangs. I installed it, not thinking it might be a little different in size. I put in 5 qts. of oil and my dipstick reads low. It barely touches the stick. I then compared my measurements between the old one and the new one. The deep part of the pan was: (old) 7 1/4" and the (new) was 7 3/4". The shallow part of the pan is: (old) 4" - 3 3/4" it slopes down. the (new) shallow part measures 4" straight across. On the deep part my new pan is 1/2" deeper. Would that make this a 7 qt. pan? And if it is, do I need a different oil dipstick and or tube? Or would I be better off getting another pan?