4.6 V8 Stuck Torque converter on transmission

[jd250]

I recently bought an 03 4.6 V8 Eddie Bauer that had a bad engine well i finally got around to fixing the engine and installing it on the car but the problem is that when i mate the engine and tranny together the engine locks up and wont spin even though everything is all lined up so i took the engine out to check the torque converter and realized that its stuck on the transmission and wont come off it does spin freely and wiggle a little but wont come off.i did make sure to see that the converter was seated in properly and before i tried to install the engine and it seemed fine but it was in the same exact position its now that i realized its stuck so im thinking it may have already have been stuck and is not something i did that made it get stuck but if it was stuck how did the old engine didn't have any issues .. i dont know what do here?? this isnt the first exlorer engine i have installed i have done many v6's but this is my first v8