No they didn't use just one gear ratio in one year. What you need to do is take the cover off of your spare tire and flip it over and look at your build codes. look for the codes that start with F.
2.86 Ratio Opt FQ3 ident PAB
2.86 Ratio Opt FQ3 ident PPB
3.05 Ratio Opt F83 ident PBB
3.05 Ratio Opt F83 ident PCB
Just make sure your doner car has the same Ratio

yep you have to look there was actually more if your trans comes from a different brand like buick etc. those two listed are good for pontiac only i believe. when i was looking the se and ssei had 2.86 and the sse or sle with regular 3800 had the 3.05 ratio. another reason why i just had mine rebuilt. my sse has the much rarer 3.05. i think the buicks, olds, and minivans and such had the same trans with different ratios.