Welcome to the site!!
As far as fins go, I don't think so! On the outside other than marker lights, tail lights and front bumper I don't think their is to much of a difference. Now you get on the inside and the differences are readily appearant, but the parts for the 70 should be alot more plentiful than they are for the 68. While the 68 has alot of interior parts that are for that year only the 70 shares alot of parts with 69-72 and even some 73-74 years. A couple of very minor differences exist on the exterior between the 70-72 years, but as long as you don't plan on making an all origional numbers car none of them should be a big deal if you get the wrong year parts. An example are the tail lights are different from 70 and 71-72 tail lights, but they readily bolt up. We could talk about every little minor difference from one year to the next, but all parts do interchange even if they look a little different than origional.
I hope this helped a little.
As far as fins go, I don't think so! On the outside other than marker lights, tail lights and front bumper I don't think their is to much of a difference. Now you get on the inside and the differences are readily appearant, but the parts for the 70 should be alot more plentiful than they are for the 68. While the 68 has alot of interior parts that are for that year only the 70 shares alot of parts with 69-72 and even some 73-74 years. A couple of very minor differences exist on the exterior between the 70-72 years, but as long as you don't plan on making an all origional numbers car none of them should be a big deal if you get the wrong year parts. An example are the tail lights are different from 70 and 71-72 tail lights, but they readily bolt up. We could talk about every little minor difference from one year to the next, but all parts do interchange even if they look a little different than origional.
I hope this helped a little.
