Series 1& 2 Barrel lengths

Im aware that series 1 barrel & piston are shorter ,but are series 2`s also shorter, certainly EIbar 1&2 and very early 3`s are .
If they are different length`s how does a series 1&2 exhaust ( listed as same on most selllers websites ) fit ? Theres quite a bit of height difference.
TIA
If they are different length`s how does a series 1&2 exhaust ( listed as same on most selllers websites ) fit ? Theres quite a bit of height difference.
TIA