hmmm since I put that much up, I might as well explain that Nissan didn't originally have a sil-80 model designation, rather it came about through drifters crashing their 180sxs and putting the silvia front ends on simply because they were cheaper...
This 'fad' caught on, and eventually got popular enough for Nissan to release a sil-80 model, which had various little tweaks for a little more HP (different cams, I think) and to make it even more tail happy than the 180sx. These were however manufactured in a very small number, and nowadays are near impossible to find.
Sil-80s are much, MUCH prettier than the One-Vias that we have here in the states, which are, if you don't mind me saying, quite ugly.
FWIW the few 180s with S15 fronts are called, more appropriately, strawberry faces. That's because "15" and "Strawberry" in japanese sound alike.
<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/thumbs-up.gif" border="0" valign="absmiddle" alt=':thumbsup:'>