I have a 96 LSS that needs a tranny and i am needing to know how to match a used one from another car.Is there only certain years and vehicles that are compatible? Is there a list of these compatibilities anywhere?

Which engine do you have?

It is a 3800 series II non supercharged.

4T60-E series. You don't have the Supercharged version, so that throws out the 4T60-E HD trans. Very common trans. You could yank one out of a Park Ave, Bonneville'* etc, but you may run into gear ratio differences. And, I'm not sure on the year range. Boosty is our tranny guru and should chime in shortly.

There is a tag on the differential end (passenger side) on the back of the trans. That gives you everyting you need to know.

does the tag info have to match exactly?

There are two different gear ratios available. If that is not a concern then any 96 NA Park Ave, Lesabre, Bonneville, or 88 or 98 should work.

I'm seeing 4 different gear ratios. But, its also dependant of the body style. Have a looky.

Ok i guess this means that only a tranny from another 1996 model will work. The one my friend has came from a 94 Buick can't remember whether it was a Park Avenue or a Le Sabre.

Uhh, kinda, maybe, not sure. Right now, I have a 96 4T60-E-HD in my 97, with a supercharged engine from a 99 Buick Riviera. Thus why my car is so confused.