I have a 1995 Cadillac El Dorado (4T80E), and I'm trying to swap a transmission from either a 1998 El Dorado or a 1997 Seville. Will either of these models fit my 1995 El Dorado?

Thank you all for your time!

Fit is not all there is to it. They will bolt up but may need other things done like gear ratio and such.

I agree with carfixer007 ^^^^^^^

. . . and keep in mind the 4T80E is an odd transaxle. Unless you're really really lucky, support for these odd transmissions is going to be thin at best. If you don't have exactly the right one, odds are good nobody around will be able to get you back running.

if i have the vin numbers to the cars would that tell me if i can use the transmission in the 98 and put it in the 95 i just need to know if they will fit or not and work

I'd be speculating if I gave you a "for sure" answer.

What I have found by digging around:

From your original list
1998 Eldorado
1997 Seville
1995 Eldorado

It looks like all three had a choice of 3.11:1 and 3.71:1 final drive ratio. That'* going to be important to discover. on the recipient and the donors.

Regarding how they connect etc., the electronics will likely be the hard part. Since your recipient is a 1995 (therefore pre-OBD2) and the others are OBD2, there might be electronic differences.

Hopefully someone with more knowledge on these will chime in.