Is there any way i could check for sure if it has the keyless wiring?
See page 8a-201-6-a of the service manual for a picture but basically the RKE module is behind the instrument panel and above the glove box (probably can see when removed.- has two 8-pin connectors, one blue and one black ). Program connector (used to program remotes) is a 2 pin connetor on the steering wheel side of the top of the glove gox opening with a black wire and a ppl/wht wire (8a-132-2 of the 90 FSM) - was wrong about the trunk.
To program or test for operation short a to b for 2 seconds on programming connector- doors will lock and unlock. Press the UNLOCK button on first transmitter - doors will lock ad unlock. If have a second transmitter, release the first and press UNLOCK on the other. Locks will cycle again. Remove jumper (page 8a-132-13).
I bought all of the pieces I need to add RKE to my Reatta on e-Bay including two Cadillac remotes (it has the anti-theft module and to use a cheap RKE would be complicated electrically. GM unit has all the right signals). So can verify that the 702s work at least for an 89 Buick RKE.
More than you ever wanted to know ?