no such thing ,, the 109 was the production block for 86-87 na and turbo 3.8,
the SG1 109 block was used in the 89 tta
theres no difference in blocks other then the SG1 casting on the side and SG1 doesnt stand for stage
the 89 tta received the SG1 109 then after the SG1 blocks used for service replacements on warranty repairs
and the SG1 109 being it was used in the TTA could have the TTA cross drilled crank