High Speed vibration, can't find what's causing it.

I run drag radials on my Dart and always put Right /Stuff silicone all around the weights to ensure they stay put . I was considering purchasing a Dakota set up for Stock Eliminator minus motor and trans but after some research I found out that nobody made long tube headers for a small block in a Dakota only shorty headers like I have in my D150. Especially since I was going to use my W2 motor with a different bolt pattern than a standard head. So I scrapped that idea would have been cool though !