Follow this guide and pay most particular attention to the 'O' ring between the TB and manifold. Believe me when I say you have to INSURE the NEW 'O' ring does not move out of that groove in the slightest. When I did mine, I test fitted it a number of times until it did not pop loose two times in a row. They will pop loose, and you'll pay the devil trying to figure out what went wrong (luckily I paid attention to the part about making sure it didn't dislodge during assembly, and did those 'test fittings' until I had two in a row that didn't pop out before attaching the 4 screws). My 74mm MOD went without a hitch, take nothing for granted and check, recheck before moving to the next step. A job worth doing, is a job worth doing RIGHT the first time. So, review the suggested post, review it again, and once more. Then make sure you have a new 'O' ring, and that it is correctly positioned before installing the 4 screws. You'll be glad you did. Just my $0.02 worth, Good Luck!