1966 Chevelle LS3 engine swap with 5L40-E automatic transmission

[bhsanchez72]

I have a 1966 chevelle and I am planning on doing an LS 3 engine swap with a new transmission. I am planing on putting a 5 speed 5L40-E automatic or a 6 speed 6L80-E automatic transmission. My question is, is there any way of knowing or does anyone know if when putting the new transmission in the bell housing of the transmission will fit in original tunnel part of the floor or will it need to be cut? Thank you for your help!

[Craig@Bowler]

I can't say for sure with the 5L40 but I can tell you that the there's no question you will with the 6L80. Typically from our experience if the transmission you're wanting to put in wasn't a factory option for the Chevelle then you will have to cut the tunnel. (Legend 5 speeds excluded) We've squeezed a 4L80 in one barely.... but that's as close as we've come.