I cleaned the model some more and smoothed some of the edge to better match the original. It might need a tiny bit more cleanup but then again I always think there is more that can be done (smile).
https://imgur.com/a/67OiN
Because this is not for a student project here is a link to the model file so you can examine the topology.
https://dl.dropboxusercontent.com/u/...215_Gis80s.rar
I hope this helps and keep working at it.
-Rick M
Regarding your question about the small offset. As I said I started by drawing all the openings using quad draw. To create the offset I then just extruded with a small offset value and then delete the faces the will be the openings. Then using quad draw I fill in the gaps between the opening (image 2). Once I had the regions with the openings created I combined the top and bottom region then using quad draw and regular extrusions I completed half the top face. Then remember to add the bend using the non-linear bend deformer and continues extruding edges and faces to complete the model.
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675
Last edited by ctbram; 23-02-2015 at 12:37 AM.