The headlight buckets are different, and so are the trim pieces, requiring either that you convert the entire front nose to the '69 or you re-work the headlight bucket supports in the fenders by removing the '69 pieces and welding in the ones from the '70 fenders. I've seen it done before by a shop although it was because they had a '69 fender on hand and needed a replacement for the driver side on a '70. The shop owner told me he would've just bought a '70 fender had he realized how much work it took to make a '69 work.