ok guys, i didnt know what searchterms to use because the "metal piece" in the "hole where half shaft goes into tranny" didn't seem very search engine friendly, especially since google kept pulling up stuff about gloryholes. normally id be fine with that, but my baby is hurting. (please ignore spelling grammar typos, as soft keyboards and t9 text predicter = epic fail). that being said, i recently did a half shaft replacement due to torn cv boots & car height dropping 6 inches.I figured since i had the knuckle off, might as well do the rotor and bearing on passenger side.(mistake #1). after not having the right tools to replace the bearing, i had the shop reassemble the knuckle and mount it. 4 days later, drivers side cv boots failed. i didnt replace rotor on this side, as it was not as worn. no shop interference on the driver side.

2 weeks later, i notice my car accelerating harder and more slowly, and the passenger side wheel began to smoke and decelerate on its own. i pull the wheel off made sure the calipers could move back and forth, verified driveaxle still flush to differential surface. everything aok, reassembled, drove fine for another two days. then, the car stopped abruptly on a highway...
i had all my gear on me, so i pulled over and repeated the same things i had done prior. i noticed caliper piston was sticking out and would not go back in. i replaced that, things were going great about two days ago when i hit a hard bump in the road. the car gave me oil pressure light, brake light but no check engine. she stopped accelerating softly again, now is leaking transmission fluid and had some heavy oil loss. 3 qts roughly. i refilled fluids to see if i could isolate leak, and when i had it jacked up i noticed there was a gap in the spot where the halfshaft should be flush to its mount. i assumed that was the issue, so i pulled the drive shaft (driver) so i could reseat it. it wont go back into its spot, there is a metal obstruction that is blocking the spline from going all the way back in. i could take a picture if necessary but it will be using a kindle fire front facing camera, i doubt it will be of any use. this whole problem spans 7-8 weeks, i have also just replaced the inner and outer tie rods due to a torn bellows boot that was discovered after the leak.
im sorry for the novel. thanks in advance! (ps, i learn quick but am poor as hell, so really trying to keep it out of shop)

 

so what is that metal piece, how can i get to it, and where should i look to fix the leak.