I have a 700r4 in my T bucket with a 3.73 rear and I love it. It locks off a switch on the dash but will only lock in OD. With a 2500 stall 3.06 low gear and a 3.73 gear this thing will go really good from a light. It unlocks with a brake light switch. Tap the brakes when slowing down and it down shifts out of OD.