To explain the one on the right in the Pic @601to602 has supplied the part closest to us goes in the gearbox and is the same splins as an inner cv joint, It gets held to where the engine mount is with bolts through those 2 holes so it cant move, It then has its own unique cv joint and the short shaft goes in there and the rest is the same as a normal cv shaft.
With your ej into your L80 you should be able to do it quite fine. Have a look at “ill minded” build thread through the daiforum link and you will see he just used his L80 gearbox etc on his and it was fine if keeping the smae standard hubs etc.