From Kent Brown, Senior Vice President & Transportation Practice Leader, Hylant:

To get an insurance quote, carriers need to compile:

1. Loss runs for five (5) years. And they need to be currently valued. That means, they need to be pulled within sixty (60) days of the expiration date. If your current insurance agent won't supply them to you, you can appeal directly to the insurance company to get that information.
2. Historical information (how many miles you've driven, how much revenue you've done in the last five years and expect to do next year).
3. Equipment list.
4. Driver list. It's preferable if you can pull the medical benefit ratios (MBRs), but if needed, your future agent can (though the agent is limited as to what they can do with them). 
5. International Fuel Tax Agreement (IFTA) reports.