can anyone tell me if a AU or BA auto shifter knob will fit an EB

not a straight swap no

whats involved?

JC on the Australian Ford Forums (unsure if he's a member on here) is making modified BA shifter knobs which fit on an E-Series BTR t-bar housing and have the detente (or whatever it's called) work with the e-series shifter gate.

Or you can go all-out like some of us here with an SSS setup