rear locked up
 

I have a 1995 Mustang GT. The t-5 was getting cracks in the casing and after a few bearings went out, I bought a c-4 and my buddy put it in for me. The car ran perfectly with the new transmission. I brought the car up on ramps a few days ago to do an oil change and to top off the transmission fluid (The guy who put it in for me said he didn't have enough fluid to fill it all the way up and it just needed toped off, and made a new tick mark on the dip stick where it should be filled to while the car was running.) I didn't know about this dip-stick and didn't see one under the hood so, when i went to top off the tranny i looked for a plug like on a manual transmission. I found a bolt on either side of the tranny that looked like plugs. (the head of the bolt was shaped like a 3/8 drive.) I pulled one out it fluid came out so i thought maybe i pulled the drain plug instead of the fill plug, so i put it back in and pulled the one on the other side and more came out. thats when i called my buddy and found out that there was a dip-stick and to fill it through there. After servicing everything i started the car and tried to drive it back off the ramps, but it acted as though the e-brake was stuck on. lifted the back wheels and with the e-brake on, the wheels did not move at all. With it off they moved a few inches than stoped as though the car was in gear (this was in Nuetral) I tried it in all gears and it did the same thing. If i put it in gear and really spool it up the car will move but still acts as though the e-brake is stuck on. I'm afraid that the bolts i pulled on either side of the tranny were not plugs at all. and may have been holding something on the inside of the transmission. I'm not sure whats going on and would really appreciate if anyone could help me out. I was just getting ready to sell the car so it really sucks that it's doing this now.