tech 2 error codes

ive got a 1995 GTP with 3.4 L DOHC getting error code 341 which is a cam sensors, which if i remember right there are 2 cam sensors , because when i removed my head gasket. But which one has to do with then 341 error code.
And my mechanic said most of my problems are in my right rear. and i have ABS error codes, 11, 28, 66, 86, 36 error codes. Should i replace everything in my right rear or all they codes related to one thing?