I am looking for somewhere that contains the data showing the differences between past futures contracts. For example, I want know the price difference between NQU8 and NQZ8. So basically if I were to pull up a chart of NQU8 I would know what to add/subtract to get the price equal to NQZ8 numbers. Ideally for at least NQ/ES going back a few years. Anyway to find such information would be greatly appreciated. Thanks in advance.