Re: installed B&M Trans oil cooler now a shudder?
What type of fluid did you use?
Some people that have gone to synthetics during a fluid change get the shudder. I had it happen in my Ty. Did the panic thing, then put regular old $1.59 a quart Dexron III in it and it went away. You may get away just using a bottle of the lubegard. There are several topics on here about it. NAPA sells it for about $10 a bottle.
Your trans cooler is under pressure. It's nothing like your intercooler. The air will quickly get pumped out and dumped in the the pan. If you see a lot of foam on your dipstick, you haven't got enough fluid in it.
Have a good Easter!