auto trans swap...

Hey Z heads,

im thinking about changing my 3 speed auto trans in my 82' 280ZX to a 4 speed auto, is this simple to do?

what thans am i best of getting & around how much will it cost?

any modifications that will have to be made, or any other info would help greatly......

also will my genie 6-2-1 headers off my 260z 2+2 fit my 280ZX (L28 E, N42 head)?

thanks a load, mellow:dead: