Does a 1970 cj3a top fit on a 1975 cj5?
Jeep didn't make a CJ3a in 1970.
The CJ7 was 10" longer than the CJ5. Most of the additional length was in the rear portion of the vehicle, so even if you wanted to modify a CJ7 top to fit it would mean taking out and replacing the windows and shortening the top. Way more work than it's worth. Keep looking for a CJ5 top, or go with an aftermarket top instead.