[HO455]

Unfortunately the C10 vs C20 difference isn't as black and white as it looks. C10's could be had with upgraded spring packages as well as engine packages. However the differences in the two packages goes deeper. The C20 frames are stiffer and more resistant to flexing. The front wheel bearings are larger and the rear axles have full floating beatings with lower axle ratios. The wheels are stronger and the tires should have a higher load rating. The downside of the C20 upgrade is a noticeably rougher ride quality. The factory offered all kinds of different suspension options for the owner who only needed to have a higher GVW capacity occasionally but wanted a better ride the rest of time.
So when you say "'ll be towing occasionally." Do you mean towing a 2500 pound camp trailer 200 miles once a year, or towing a 4500 pound loaded car trailer 50 miles 4 times a year? Is the terrain you plan on driving over mostly flat, hilly, or mountainous? If I was towing in the first example then I would be comfortable with a properly set up C10. In the second example a C20 would make me happier. The days when I would tow a truck 1500 miles behind my GTO are long past.

There is more information on the GVW ratings of our trucks at the GM Heritage Center website. If you dig in and look at options there is a lot of information there.

https://www.gmheritagecenter.com/gm-...tion-kits.html