3000 has a post thru the dinette supporting the mast
3200 I believe is the same length but restructured with the bulkhead ahead of the dinette supporting the mast.
3400 is basically the 3200 with rear steps and underhung rudders. This is actually a couple feet longer. It's a mix of outboard
and diesel/IO drive leg.
105 is a completely new hull
design same length as the 3400 and similar layout but with plumb bows. Early ones were a mix of outboard
and diesel/IO driveleg...then after a couple years it was all diesel/IO driveleg but many have been modified to go back to outboard. There are several sub-variations of the 105 that are mostly interior
One thing about Gemini's is they truly "evolved" over time so even the same model may have some changes from a sister ship.