You can use the following recursive function which will work even if your lists are more than 2-levels deep

    getElemsR <- function(dat, Index, Lev=2)  {
      if ((Lev <- (Lev - 1)) > 1)  {
        inds <- seq(length(dat[[1]]))
        dat <- unlist(lapply(inds, function(i) getElemsR(dat, i, Lev)), recursive=F)
      } 
      sapply(dat, "[[", Index, USE.NAMES=T, simplify=F)
    }

    # get the 2nd element of every 2nd-Level list
    getElemsR(myData, 3)  # Lev=2 by default

    # get the 2nd element of every 3rd-Level list
    getElemsR(myData, 2, 3)

    # if needed as a vector:
    unlist(getElemsR(myData, 2, 3))

<hr>
Alternatively, if your lists are only two-levels deep, you can use a simply sapply as @Romain pointed out. 
You can wrap this in a function 

    getElems <- function (dat, Index)  {
      sapply(dat, "[[", Index)
    }

    # get the 2nd element of every 2nd-level list
    getElems(data1, 2)

<hr>
Sample Data

    data1 <- lapply(1:3, paste0, c("A","B"))
    data2 <- lapply(4:6, paste0, c("A","B"))
    names(data1) <- names(data2) <- c("_sub1", "_sub2", "_sub3")
    myData <- list(Lev1A=data1, Lev1B=data2)


#========================#
$$$$$$$$$$$$$$$$$$$$$$$$$$

  $$$  THOUGHT PROCESS $$$

dat <- data
goal <-2  # every 2nd element

# L ==3
# LEV 1,  length(Lev 1) == 2
z1 <- getEls(dat, 1)
z2 <- getEls(dat, 2)
(z1)
(z2)

# L == 2
# LEV 2,  goal is at Lev 2 (ie, Lev=3)
r1 <- getEls(z1, goal)
r2 <- getEls(z2, goal)
c(r1, r2)

data - L =3
dnormal - L = 2

dat <- data
Lev <- 3
# TRANSLATES TO

#============


# the second elements of all members
1B, 2B, 3B, 4B, 5B, 6B
Lev=3
dat <- data
uindex <- 2

2:  length(dat)
3:  length(dat[[1]])
2:  length(dat[[1]][[1]])
1:  length(dat[[1]][[1]][[1]])

Lev = 3

Index <- length(dat[[1]])
dat<-
  sapply(seq(Index), function(i)
    t(sapply(dat, "[[", i)), simplify=F
  )
  dat

length(dat)
unlist(dat)

  t(sapply(dat, "[[", 1))
  t(sapply(dat, "[[", 2))
  t(sapply(dat, "[[", Index))



#===============

 sapply(dat, "[[", c(L2, L3))

 sapply(dat, "[[", 
    sapply(1:length(dat[[1]]), 
  )