Sorry to hear you got so screwed with your trans. But if they took it apart and then slapped it back together, you're not going to get much out of it. Nevertheless, if you can move the back of your trans enough to remove the B2 cover and you drop the pan, you can probably see if the problem is with the B2. There's a thrust pin that fits into the piston assembly on one end and the other end fits into a socket on the B2 brake band. Check the piston and bore for wear, also the rubber seal that is pressed into the case in front of the bushing needs to be good and seal on the smaller diameter of the B2 piston.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.