Hi all
I'm Trying to track down a pair of one piece headlights for a 1990 Honda civic sadan
can anyone help ?

 

If it's for a USDM front end, I don't think such a thing ever existed in the aftermarket.

For a JDM front end, this took me < 10s of searching:

JDM honda CIVIC EF2 4Doors SEDAN 1piece HEADLIGHTS (R) lights SH4 | eBay
JDM 6568 HEADLIGHT (PLASTIC LENS) HONDA CIVIC EF2 SH4 MODEL 1987 91 FRONT LEFT | eBay

 

JDM one piece headlights. Odd one coming up in US priced around $160 plus postage going to open my own ones to see if they can be refurbished
In the meantime I will be on the lookout for a pair priced right

 

For better or worse at this point, I'd say anything < $400 a pair for something clean is going to be a fair price point. Old cars are tough to get nice parts for.