Seeing as your prevous post has wander'd a bit the answer to your question of length is 12'' give or take an inch.
I have a Mantua logger but am using tthe Roundhouse short vanderbilt tender,sure its really close to the USRA tender that is stock.
At any rate a 16'' TT will more than suffice....
Soon as i have the time I''ll drag out an old artical i have stored someplace
and finish the kitbash i started a few years ago, mating a mantua mikado boiler to the 2-6-6-2 running gear for a real heavyweight drag freight locomotive... ;D
Well thank you! That is convenient! That means I only need a 14" turntable! And since I was going to buy my turntable from www.cmrtrain.com. The price dips at the 14" length. So I'll go with that. And Gene, I'm sorry but I'll have to kindly turn down your offer over the turntable.