there are 4 boxes, 197 original, 197 revised 6th gear, 200 original and 200 revised (the one you want but not sure when it was introduced).
If it has had a box replaced IT DOES NOT GET A NEW GEAR BOX it gets a reconditioned one and the original one sent back to be reconditioned.
my 197 had 30K ish on it without issue and the 200 has 31k on it and ok upto now.