In order to install the stock High wing on a wingless trunk, is there a gasket required or is it just drill and bolt?

 

I think, from recollection, there is a thin gasket to keep it from gouging and sealing it nicely.

If you haven't already, you might be able to swap your trunk with someone who is looking to go wingless. That would save you trouble in drilling.

 

Is the gasket reuseable? Or should I look into getting another one?

 

Use 3m rubber/foam strips that have adhesive on one or both sides. It doesn't have to be very thick, like 1/8" or so. I believe they make circular ones that you will need to put around the bolts so water doesn't get into your trunk.

 

There's gotta be an official Mitsu part for this, no?

 

nope just cut/apply the strips for ultimate sealing power