I had 3.23 to 4.30 in my purple car over the years. At first you think you are going to drive it a lot,but now if I put 500 miles a year on it its a lot. I ended up putting a 4.10 Dana in it and love it. My blue car has 3.55 in it,but I drive it more,about 2000 miles a year. If I ever get the 70 done it going to have a 3.54 Dana in it.Because thats what I have for it. If you are going to drive a lot,2500 miles or more then go with 3.23,but I bet you will end up changing to 4.10 because these old car do alot of sitting and 4.10 are a lot of fun on the street. Just my