2000 Olds Intrigue Trans Identification

I went to purchase a used transmision for my Intrigue and was told there are a few diff tranny's for this car. Where do I locate the numbers and or letters to identify what tranny I have? 2000 olds intrigue 3.5

The trans shlould be a 4T65-E with 2 different final drive gear ratios. Find your RPO code sticker. (in the trunk on the spare tire cover maybe) Check for RPO M15 which will indicate a 4T65-E. Then FR9 for a 3.29:1 ratio or F83 for a 3.05;1 ratio. You can also write down all the information on the trans id tag which is on the right rear side of the trans between the forward band servo cover and the right axle.