I was wondering if you could put the body of a Yokomo 1/10 scale car and attach it to a Tamiya TT-01 chasis without having to cut holes for it to fit.

In short.. no
Yokomo Body poll holes and TT-01 Body pole holes are a Little Different.. You would need to make new holes...

HPI shells will also require New Body pole holes to suite the TT01

If you get a brand new shell, the holes aren't precut so you put'em where you want'em. If you're getting a used one, then it'll depend on what chasis the person was using it on. So, yeah, sure. Get'r'dun

Do you know of a website that sells the bodys of the cars without the holes cut? And also do you know if they sell a S15 slivia body and a GT-R skyline body for the TT-01? Nissian makes all of my wet dream cars; silvia, skyline, Z, and supera "sunny".

for the rear you will need to drill new ons like right in front of the wing on the paint part(not window). I didnt have to do that with the front row though

Any website that you order bodies from will give you them without the holes precut. I've yet to recieve a body (except for the cars that I had FULLY pre-assembled) that has holes cut. There may be demples but all the cutting and painting is up to you. If you want Yok bodies, try Yokomousa.com. HPIRACING.COM and ehobbiesonline.com (I think that's the site). Also, google tower hobbies. All good spots to get bodies for. If you run into your local hobby shop, you can find clear uncut bodies as well.