I predict you'll hear more about how that is too much trailer for a half ton than you will meaningful input germane to you question. But icbw.
My only comment is 16 - 6 speed, 17 = 10 speed + more power.
The best 6 speed half ton trans out of the big 3, IMO, but unless the 16 was a "deal", I'd have to opt for a similar age with the 10 speed.