Yep, you have the high torque ZF. Pretty much any Mercon V will work fine in that transmission. I would use RedLine's High Temp ATF for it's slight increase in viscosity and ability to withstand quite a bit of heat. If you don't tow or tow light any ATF will do, remember to change it "often" as there is no filter and the ZF 5 speeds run hotter due to no external oil cooler unlike the newer ZF 6 speeds.
