Ok so I was just wondering what fluids you put in your doublers bc I doesn't seem like the seal btwn the TH400 and the 203 is enough to hold out automatic trans fluid........so my question is are y'all putting trans fluid or straight up gear oil in the doublers and also roughly how much in each box?

Thanks guys, I searched but i couldn't find this specific info

Jeff

The seal holds the tranny fluid in the tranny. ATF actually works well as a gearbox lube too, but many people choose 80W-90. I've seen people use everything from 5W-30 engine oil to 75W-140. The tradeoff for heavy oil is more power consumed to turn the gears and slower shift lever action.