Unfortunately, the GPS unit can't use 5 volts. I found a chip from On Semi Conductor, MC74VHC1GT,
which looks like it will do the trick.

Strange thing I noticed:
I have an Atmel AT45 memory chip connected to PortD (D0,D1,D2,D3) and it works fine. This is
weird because PORTD is all schmitt triggers as well in I/O mode and the Atmel memory chip runs at 3.3V. It
shouldn't work but it does [scratching my head]