quesswhatidrive

OK if u dont know im doin a auto to manual swap and i cannot get the driveshaft into the manual it goes in about a inch or so then it will not go any farther, if i go back to the auto, it slips right in i have tried all 28 different ways to put it in and it will not go, is the end of the shaft thicker for a auto then manual? i was under the impression that it should be the same. any input would be appreciated thanks