and in response to the title of this thread:
All bonnevilles since 87 have 4 gears.
Which is 3 + overdrive
But it is important to note that all of them also had torque converter clutch lockup.
However whether you personally feel that the TCC means 'another gear' to you or not is a matter of self-pondering of what your definition of "gear" is in your auto trans.
If you think a gear in this case has to mean a clutch and a band then no the TCC doesn't cout (this is how the rest ofthe world usually takes a gear to be)
But if you take "gear" to mean a different drive ratio then the TCC is another "gear" in that definition.
At that point (if you come to your own mental conclusion that the TCC is a gear) then you still have one final hurdle to jump: This one being "Is the fact that the TCC is available in both 3rd and 4th gears mean that my bonneville has 5 gears (1+2+3+4+4/TCC) or 6 (1+2+3+3/TCC+4+4/TCC) Although I would have to argue in that case that No, even by your definition of 'gear' you still only have 5 gears Because when TCC engages (regardless of whether the car was in 3rd or 4th) you still have the same TCC drive ratio.
I hope that didn't confuse anyone.
p.*. as far as my personal opinion goes, i'd tell someone that "my transmission has 4 speeds but actually has 5 when you count the TCC"
... any questions?