Exhaust help for old GS 1000 1983
 

I have recently bought an old GS 1000 G from 1983 and it is with the original exhaust system 4/2
I am looking for buying 4/1 and I have seached on "the big internet" and a lot is found for GS 1000 from 1978-1981
and when I ask seller if it will fit my GS 1000 G from 1983 they write the same comment fits 1978-1981 ?
and I really hope that someone can help me with this, but is the enigne not the same for all GS 1000 models ?
meaning that then the exhaust found then will fit mine from 1983.?
I hope my question makes sense and I am looking forward to hearing from you.

All the best from Denmark