t-19 or zf-5

I've seen some well argued reasons for the t19, and perhaps it would do better off road or arround town, but if you do a lot of highway, especially a diesel, I wouldn't even consider it, the graney to over drive box is wonderfull, I have put a lot of miles on them, not sure just how many, but probably 20,000 without a problem other than the weak earley shift arm, and I'm not easy on them.