I just replaced the cover & the vents on mine over the last two weeks.
If your replacing the tank vent caps (2" pipe covers), I'd suggest going with the cyclones
If your replacing the "standard" fan vent cover (14" x 14"), they are "universal" but there are three different types (they have different SKU's)
Climb up on the roof and look at the hinge on your vent ...
A) Segmented? or 1 piece hinge
B) Bend tabs on the end or no
I don't see the year of your trailer posted, but I'm pretty sure that your model came out in mid-2000 & the hinge will be the post-1994 Elixer
Match the hinge type on the replacement & your set.
Replacement of the cover;
From inside on trailer ...remove screws from outermost perimeter to innermost perimeter
A) Open vent cover fully
B) Remove crank takes phillips screwdriver
C) remove 4 screws from exterior shroud (outermost) ..remove shroud
D) remove 2 screws from screen holder, remove screen
E) remove 2 screws from activator assembly, pull down on assembly to remove.
You can now move the actuator arm from the slide and remove the actuator.
Go up on the roof with a set of needlenosed plier and open the bend tabs so that the line up with the main-hinge (or just bend them back as far as you can. The hinge should now slide off when pulled from left to right (or right to left).
New cover will slide on the same way.
Now bend the end tabs to keep the cover hinge from sliding,
Climb down and re-assemble the interior parts in reverse order.
It's about a 15 minute job if you've never done it before, have no mechanical aptitude and take your time
However, if your installing a stack cover, or a maxflow upgrade ....someone else will need to pipe-in and advise ..... I've never changed/installed either of those.
Also .... I'll make my shameless plug ...... if your going to go through the trouble of removing the Chinese galv screws, go ahead and make the trip to Home Depot/Lowe's/Ace and buy stainless replacement screws. Then stop at the local toy/hobby store and buy a small jar of Testors gloss white (or beige... under $2.00) enamel model paint & a $.49 model paintbrush. Replace the factory hardware with stainless and paint the screwheads to match what they were before.
Also, while you have the vent fan interior shroud off ... do any sealing/caulking you deem needed, once you remove the shroud. It was absolutely scary how piss-poor the cutting/sealing installation job was on my bathroom vent fan installation (suspect the installtion guy was simultaneously drunk, was partially blind and being tasered while installing the vent fan in my unit