yip the auto will fit coz i did mine (3.5 v8, 4speed auto and defender transfer box) works a treat but you'll have to move the chassis engine mounts forward what i did was
1, cut mounts off the chassis
2, fit the engine transmission and transferbox in the chassis and bolt the transmission mounts in
3, fit the engine mounts to the engine lower into position and weld the mounts back onto the chassis
job done even the props lined up and boltted straight on.
i'm running 35-12.50X15s and with the 90 transfer box and the auto box it runs a treat