i was thinking about putting a s15 front end on my 91 240sx,and then converting the rest of the body to a s13. Willi have to have a lot of molding done or will it fit fine?

 

jspec.com will have everything you need, and give you an idea of what's involved for a '91.

 

You could mold if you want, but it isnt nec.

 

The more time you take to test fit, and mould in body panels the better the look. If you are going to spend the time and money,make it look the best you can. Like Jynx said it's not nec. but makes it look a lot smoother. Good luck on your project.