It has to be the Refited BC304s
The text hasn't been updated since the refited 304s were introduced to the mod

I've tried bc304 everywhere but can't seem to find the refit is it a specific planet i need to use?

My game also crashes everytime i win at Dakara has everyone else had this?

Yeah the option to upgrade didn't show until well into turn 500 and i'm not really sure of the trigger though once it happens you'll need to take I think it was the odesy to Othala then return it to Earth to trigger the upgrade chain.

I have the Refited BC304s, From the first Asgard planet I got
And I did take the odesy to Othala and back to earth too and notthing happen
But is there any way to get the beam weapons ? or they not in the game ?

it comes from an event you get sometime after launching the Atlantis expedition and you have to of destroyed all the replicators

it will prompt you to take odyssey to othala where you will have to pay for the refit

no refits are free

how do i even get the Atlantis expedition to start?

Every time I've done the Campaign I have gotten the BC-304 MK2. You need the Odyssey and Othala to get the 304 MK2. An event that triggers that is somewhat random, all I know is that you need the Odyssey and some time afterwards the event triggers. You need to send the Odyssey to Othala, upgrade it, then send it back to Earth and buy the Tech that allows you to gain accesses to the BC-304 MK2. However, You can not build the BC-304 MK2, in order to get them, you need to send any BC-304 to the nearest Planet with an Asgard Shipyard, then at whatever Asgard Shipyard the BC-304 is at you will get the option to Upgrade it to a BC-304 MK2, there is no limit to how many BC-304 MK2s you can get as far I'm aware and i don't think you need the Atlantis Expedition to do it. If you want to get the Atlantis Expedition, I believe you need 2 ZPMs on Earth to trigger the tech option to create the Atlantis Expedition.