Calculating the Required Size for Your Future Toter Bed
11/17/2015
Below is a body build calculator (spreadsheet) which is set up as a Microsoft Excel worksheet via an older version of Excel that will help you lay out and calculate the correct size toter bed for your specific requirements "IE - to accept a car, motorcycle/cycles, golf cart or possibly a large drom box or upright storage cabinet".
The worksheet was originally set up by Joe Johnson to help layout a bed for his T2000 then Jack Mayer expanded it to cover the Volvo VNL610/660 & VNL770 with the addition of the "body calculator."
If you own a VNL630/670 the measurement "BBC" = front Bumper to Back of Cab measurements - in the calculator should be the same -or- Very Close to the same as the BBC for the VNL610 & VNL660 as laid out in the calculator and the same goes for the BBC on the newer VNL780/VNL730's in comparison to the BBC for VNL770 that's also in the calculator.
BTW, if you run into problems using the calculator or need additional information about using it, I'm sure that Jack Mayer will be more than happy to answer your questions if you contact him at 
Toter Bed Body Build Calculator
An excellent presentation on Bed Design was mage at the 2008 HDT Rally.
2008 Bed Build.pdf
As a PowerPoint file, recommended for the animations.