threw a LS 6 in a 96 sonoma having issues with O2 sensor R r

[scotty2hotty]

I am hoping someone knows about O2 sensors then me.I have a O2 problems with pass side rear bank coming up on reader.I looked up number but cannot seem to find cross over number I post what I have .
I wondering with the O2 numbers if someone may know what it should have and why would it fail as new units low miles on her like 3000 miles
It runs great loads of pull & decent mileage with 8.5 10 bolt rear rear end 307s in there.Like 70 MPH 1900 RPM love that.
DELPI
25027985
under in smaller writing is 2533 W33 This sis the one that brought up the code but cannot find cross over number to replace it.It failed on a reader I wnt to Oreillys
auto store.
front pass side is no maker but # is
assembled in USA
53060 under that is
05k07
I was told this engine came out of 2002 vette but being back in my truck now so far i cannot even read number on driver side to check.
seems to run great a little black so lean I am thinking was found around the 2 sensors i took out & tail pipe has black there too at the O2 sensor clean them as were not bad just a tiny pit of scoot
I am new to this whole fuel injection think but sure like how it runs i guess i should learn more now
I wonder if just could be faulty sensor does that happen much
but really do not know what these came out of even
Has a 4 pin flat connector
Any help would be great as I have little experience with these so do not want to order a new one as may be bad if I order wrong one.Thanks Guys