Anybody know what kind of sub box will fit in my truck?

[Destructo]

I would like to get a dual 10" sub box or 12" box for my 85 truck, it will probably have blazer buckets in it, so that should give me some more room, its currently pushed all the way forward to clear some 6x9" speaker boxes. I may be willing to go with one good 10" that can hit hard, but we all know 2 is better than 1 I think 10" would be ideal, not sure what kind i'm going to get yet though, or what kind of amp, or where the amp will go.