sanding my camper top?

[npor]

I just recently picked this camper top up for $100



I was wondering what grit sandpaper I should use to sand it with? The clear is all pealed off the top, and I didn't know if I should use a more/less abrasive grit on the parts of the paint that do have clear, versus the parts that do not have clear. I'm going to eventually paint the entire truck a satin black, (everything, truck, grill, wheels, everything) and I was going to go ahead and start with the camper top.

[Gyuri87]

I just learned a little bit of body worked having spent a lot of time at the body shop when my car got repainted and I pretty much know how it works now but I keep forgetting the numbers behind the sandpapers I used I'm pretty sure though that it's 180 and that it will do the job.