Before I go on, I should note that even if you are mainly looking at them from a background/design perspective, I would definitely recommend having a look at the
SFB Y-modules; they include a lot of useful information about the early Fed (and early ISC) fleets flown before the advent of unified hull designs, as well as the first generation of "new" ships which superseded them before the modern era came around.
So far, there are a number of Terran hull types in the three Early Years modules.
Two of them continue, in some shape or form, into the modern era.
In the case of the light cruiser, it started as the
Province-class sublight CL, then recieved a series of warp engine refits (WCL for the first warp refit, YCL for the second, and CL for the "modern" version).
The Terran old destroyer looked, from the outside, the same as the later Fed POL; it had a very different internal configuration, however. (The original sublight DD, and the W- and Y-era upgrades, had features like armor; when the modern POL was being designed, the engineers gutted the ship design and basically built a while new ship which happened to look the same from the outside as the old Terran destroyer.)
The other Terran hulls (dreadnought, heavy cruiser and frigate) are each based on specific miniatures from
Iron Crown (the developers of
Silent Death), made available under an agreement between them and ADB. There is a list of exactly which ships were used for the three Terran hull types, but I don't have it to hand right now. You can see the outlines on the SSDs, and on the countersheets of modules
Y2 and
Y3.
(The ships of the five pre-ISC planets have the same origin; they were all based on pre-existing ICE minis. I don't have the list of those to hand either, sorry.)
As an aside, if you are interested in the Terran ship designs, I might also add that another empire in the wider Star Fleet Universe makes heavy use of Terran-derived designs; the Federal Republic of Aurora, founded when a Federation colony world was transplanted in Y130 over to the
Omega Octant. They would use the CLs and POLs they had in-system at the time of transferance (as well as a few "additions" from other sources later on) as the basis of an entirely new navy.