th350 trans, too much fluid really bad?

[knightowl73]

since i got this truck the dipstick had been messed up and one night me and a buddy made one from another one. we were drunk, so was never quite sure if the line we put was actually correct, and the original dipstick might have even been the wrong one.

well the trans has always leaked, and ive always put in like a quart every week considering the spot in my driveway just to make sure, even though its never slipped. well today i noticed that it hadnt been leaking as i had no fresh spots in my driveway, and emembering that ive neglected it for two weeks or so, i put in two qts. now seems like its either slippin a bit, but really just feels like im pulling a trailer or something. so i was wondering if maybe it was finally at the right level and not overfull like normal possibly, and ive put in way too much this time. is too much trans fluid really bad? id drain some to what i believe is the proper level but then i am scared it will be low, as i do drive long distancs in his truck on weekends. i know the first thing is get the right dipstick and tube. im also gonna drain it and put new fluid, so how much does a non-lockup supposed to take after draining? and is there supposed to be fluif in the tailshaft housing when i pull it off? last time i did when i fixed my speedo gear there was about half a qrt in the tail. was that an indication of too much fluid?