OK I dropped a lt1 in my 87 firebird originally a v6 no harness in car got the harness and ecm from the donor car a 95 roadmaster but the guy cut the wires at the firewall that go threw to the inside of the car I need this car wired everything else is already done plz help

 

I would first start by searching for LT1 swap threads and figure out what you have and what you need to get it wired, there is tons on information on this swap. once you get the basics on the swap down you can ask specific questions on where you are stuck and needing help.

If modifying the harness you have seems like its going to be to big of a task you can always buy a aftermarket harness that makes things much easier.