870 isx replacing a 871isx.

[herschel]

ok first problem the 60 pin connector on the engine harness will not plug into the 871 computer. the V shaped plastic pin is a quarter of a turn different than the 870 ecm. now does this mean that i should try to change the complete engine harness to the 871 style or is the volvo engine harness the problem and i need a pete 870 engine harness? going to be alot of stupid questions on my part sorry!