Hmm, you know - I'd say this detail styling is getting closer to that of your medusa now, and that's a very good thing.
Since I last saw it, you've replaced the curved top and bottom surface with a series of flat ones, so the cross-sectional shape of the engine block is no longer kinda lip-shaped, but is now more of a bevelled octagon - and I would say it looks hugely better for it. The engine block is DEFINITELY beginning to resemble an up-armoured Fenris.
I do have some suggestions here which I'll go through below with piccytures!
1) I really like the recessed and segmented look at the front of the block. It fits in fairly well with the original style there and just looks freaking cool. My suggestion is to take it a little further and add another plating segmentation line around the hull as I've drawn onto your pic. You may need to shift some details back a bit to make it work (or possibly squish the curved sections in front of the line forward a bit - whichever works).
2) The 3 little round things I reckon could easily be neat little escape pods if you haven't already intended them to be, and my initial thought was that although they definitely fit......at the same time something didn't feel quite right. Then I opened the current model and saw - the big lights! The lights are a very prominent feature of the fenris/levy (and they significantly affect how the ship looks in dark scenes), and so I think bringing them back would be really good. They also nicely frame and integrate the escape pod structures (plus they kinda make sense - ie, lights are where people are, escape pods are where people are).
3) Not really a model suggestion but still worth mentioning: the colours...or rather the tones of grey. These I think will play a major role with the feel of the aft section based on the texturing. If you imagine the 'flow' of the engine block is fore to aft, the darker recessed part on your model is flowing in more of an 'around' direction. The more contrast between the recessed section and the raised hull around it, the more the 'around' direction will become the dominant direction of the whole engine block, which I don't think works as well for the design of the ship. Currently style wise there are many prominent fore-aft lines over the whole design, with 'around' lines having a much less significant role.
So basically my suggestion here would be for whoever's texturing it to keep this contrast down to the kind of level pointed out in the current textures. Ie, there and visible, but not overpowering enough to change the flow of the engine section.
Finally, about the engine nozzles: to be honest I really really REALLY don't think they fit at all sorry. Normally I love circular engines - heck I stick them on most of my ships! Here though I think they do break the style very badly. The big one just isn't a good use of area on the rear facing part of the engine block and makes me think more of a 'rocket ship' than a 'warship'. The little ones...yes they make sense from a rotational point of view,... but they just look massively out of place.
Here's a side by side comparison: (Including the original too for fairness)
[V] tended to do either flat vents or round nozzles on terran ships. Hippocrates, iceni, elysium, colossus, deimos etc all have definite round nozzles. Other ships such as the fenris, orion, triton, hecate and aeolus have definite flat vent style engines. This effect I think has been lost a bit since retail, since our thruster effects currently favour round nozzles, spewing huge amounts of glowey stuff backwards. Originally they just kinda glowed and flickered.
Style-wise the vent style engines are much more suited to this kind of glow:
http://images.wikia.com/stargate/images/b/b6/MyancientshipOrion_2.JPGNot entirely sure how we could achieve that but I'm sure it's not far off if not already possible.
So yeah - I'd really strongly urge you to reconsider doing a vent style. It doesn't have to be just a grating like the current fenris model (which is actually a stolen section of the faustus' solar panel
), but you can definitely make some interesting engine-y structures that don't look like round nozzles.