Pulled an engine after blowing one up, engine rebuilt and installed but the drive will be the death of me. Slides fine into the gimbal but will not mate and slide together all the way. Still about an inch gap. Been fighting this issue for 3 fdays now and need suggestions.

i have found that 6 drives need to be all the way down[trimmed in] to get the input shaft to slide in.maybe the 2 drive is also this way.

You sure the male shaft is going into the trans? Are you rotating the propshaft while jiggling the drive up and down a bit? Sometimes you may need to wedge something under the helmet to get it to a more horizontal position, and masking tape the u joint assembly up to keep it from going limp and falling. Be careful not to damage the tailstock seal