Yeah don't even say what speed you where doing, just work on proving that the truck cannot even do the speed you are accused of. You can go online and print a topo map of the exact area you where pulled over at, a topo (topographic map) will show elevation data, and will show that no hill was present or big enough for you to get going to 67 mph, and simply a notorized letter or company rep will easily be able to tell the courts that the truck is governed at 62mph which therefor makes it impossible for you to go 67mph.
The company would be foolish to just accept that ticket. If you had all of the proper paperwork to show the truck was legal, then there is no reason for the company to just pay it, it will effect their safety rating. Even though they are two seperate tickets and two seperate cases in court, you can still use that ticket to your advantage to discredit the officer by proving the truck was legal at the time aswell.
Personally I would recomend joining one of them driver legal plans, the one I know of is $3 or 4 a week, and for a ticket such as that I think they only charge $100 to represent you. check it out
Drivers Legal Plan
I haven't joined their plan yet, but I am going to very soon, and as far as I know you can join them and still get the special price even after the ticket happened.
Hell if you cannot afford the $14 fee to sign up and $100 to get the lawyer into the court room for you, then you need to re-evaluate your job situation and or lifestyle