I bought my truck with a T19 and GV unit under it. I have to say I am personally not all that fond of the GV. It is clumsy to use compared to another shift position on the transmission and the "split" gears is more like "split hairs" with the close ratio transmission. That said, I am going the double overdrive route (ZF-5 plus the GV) because of my 4.10's. If I didn't already own the GV I would do the ZF-5 and re-gear the axles instead. I just thought I'd throw in here since I have lived with a T19 and GV for nine years now and have not really cared for the rattling little red lever and the rougher than normal OD shifts... and remembering to reset the lever when you are in busy stop and go traffic etc., I have even contemplated selling mine to pay for re-gearing the axles but that is a lot of additional labor. I will stick with what I have, but I wouldn't buy a one new.