[john]

Terry,
Their are a couple of units made for truckers but after checking under their name/complaints I don't think I would pay the extra bucks. Too many unhappy customers.
Tom-Tom is good and even the middle price ones can be used while walking.
Garmin has a fairly good deal on upgrades as long as you own the unit. Others might have as good of a deal.
It still depends on how much you want to spend. Than do research on the one that looks good.
I found going to Google search and type in the product name/complaints is a lot of help.