My tares are both set to 0:0 (for small packages and for large). The amt that "Estimate Shiping" gives is different from if I go to the UPS site.

I did determine that if I go to the UPS site and enter the exact same criteria, WITHOUT specifying the dimensions of the package, then the rates are the same.

But if I specify the dimensions on the UPS site, ie. 6x6x6 inches, the rate there (shipping from MA to CA) jumped by $10 over the rate in Zen-Cart.

Also: on the UPS site, if I ship within the same state, 2nd day air isn't even an option (as they give 2nd-day service for ground shipments within state). But the Zen site quotes this as an option at an additional cost of about $8.