transmission mounts · 1970-72 use rear transmission mount #12652 for turbo 350 ... · 1973-78 use rear transmission mount #12653 for turbo 350 ... factory heads do not have bolt hole in end holes must be drilled and tapped to ... frame mount #12677 use factory stock rear transmission mount 133 header dual ... length 17 136 modification of rear crossmember necessary for installation ... the california vehicle code for 1975-82 chevrolet/gmc trucks and blazer/jimmy equipped ... frame 154 dual kit exits in front of rear wheels 155 will not fit manual ... not seal properly on heads with the end upper bolts lower than the center bolts ... heads 225 this systems exits behind the rear wheels 226 will fit c-6 transmission ... 238 fits both lt-1 engines and standard chevrolet small-block engines 239 requires use of ...