I should have said that there are many different options when converting to 48v. Different controllers, POT's, Batt - combination, wire size. All that stuff.
The gent's here have great knowledge from doing these and learning themselves.
To keep things from bruning up the needs are:
1 - 4 guage wire
2 - 48v 400+ amp controller
3 - POT
4 - 48v 400 amp solenoid
5 - 48v F/R switch
6 - 48v charger
7 - plus fuses & diodes
Pretty sure I captured it all from what I have been reading.
If I missed something, please chime in!