I built this model a few years ago, but it needed some corrections. This is how it was looking about month ago:
The fin base had wrong shape - it was clearly visible when the base was painted blue. The nose was canted up a little - my mistake. The prototype was standing in the back of my display cabinet. Finally I decided to correct the fin. I bent it a few times until it fell off, cut the base from the upper part and added some plastic between them to get correct angles. Then I realized that the new shape is almost the same as fin of the production F-16A/B. I found a statement in the net to support this. Luckily I had F16A/B fin spared from Revell F-16C... So I put my corrected fin away and simply used the production fin - Revell did it better than me. I painted it with some part of the fuselage. Decals came from another YF-16 kit (the rest is enough to portrait the second prototype - stay tuned).
Correction of the nose was more risky - I had no spare decals to replace them if damaged. But I could not stop half way, so I cut off the snub nose and corrected the angle. Decals were not damaged during sanding of the scar and repainting the nose. Now my YF-16 is looking much better: