Sorry, but your dead wrong. None of these cars ever came with a 6 speed period. The only manual trans available was a T5, 5 speed and that was only on a 305. The 350 cars only came A4 end of story. Take a picture of the front brakes, if it doesn’t have dual piston calipers and 12" rotors in front it’s not a 1LE car plain and simple. Again not trying to be a dick, but I know these cars better than anybody on the forum. Also the correct RPO code and designation for the 350 is L98.
1LE cars also had an aluminum driveshaft and some other changes. They could be ordered with or without A/C and radios.