Originally Posted by marco polo
Don't know if they're still available, but a word of caution (which you'd want to confirm), but I believe that you cannot create units on your PC and upload them to a 378. If I recall, I think it had something to do with the maps that were pre-loaded on a 378.
The problem with the 378 is that the inland waterways are somehow tied to the maps in the GPS. Therefore the map on your PC will never "match" the GPS maps and when you try to send a "pre-calculated route" to the 378, it will always want to re-calc it using the info it has on the GPS. Kind of similar to what the 60/76 series do also. You can sort of get it to go where you want by inserting enough way points and sending a direct route that makes sure it uses all your points. You are still leaving the final calculations up to the GPS, but its possible to pretty much get what you want.
I can't remember though if because of the way the maps and inland waterways are tied in, can you even update the internal maps on the GPS very well? Either way, it does have its quirks and for road routing, the 478 is considered a much better option.