What would i need to swap a 5speed into my 81 diesle rabbit factory 4sp? would i t ahve to be a 5spd form a diesle A1 ? or could i use a gasser trans and could i use an a1 or an a2 ? i know il have to get a 5sp shifter also but mainly wondering what kind of cars i can used the trans out of? also what kinda milage / power advantages could i expect?