The only questions you are not responsible for on the 135 test are the part 121 FAR questions. The performance ones are fair game. My part 135 test was 80% questions on the MD-11, 767, L-1011 etc. I called Gleim and asked about this. Got to talk to the man himself....Dr. Gleim. He said yup....study everything but the FAR chapter of the other test. A certain percentage of the 135 tests (apparently mine included) MAY have quite a few "121 airplane" performance questions, and vie versa.