Are you able to use the OD gear in your TH200 at full throttle high speed? Only reason I'm asking is because when I've had TH200s an TH700s they would not go into or stay in OD past about half throttle. IIRC GM made them like that because the OD clutches and hardware were not beefy enough to withstand high power. That's one big advantage the Mopar A-500 and A-518 have over their GM counterparts, the OD units are plenty big and beefy.