they are both the same chassis
you could take two modded SHO's, each a gen 1 and a gen2 and put them on lifts and look underneath and you probably can't tell any differences... unless your a SHO looney and can spot minor differences a mile away
especially if they both had the same brakes/knuckles, shifter, exhaust, rear brakes(older ones had vented rear rotors)
there is not much that is different between the two. The actual metal unibody you see around the trunk and rear bumper is different. The front fenders/hood/bumper is interchangeable. Most things besides the rear are exchangeable/bolt on between the two gens
surely there are interior differences, wiring differences, EATC differences, etc.... but the physical parts of the car are like 95% the same.
you can swap subframes(even gen3 ones swap over), rear suspension parts, interior parts, steering and brake parts all the dimensions are the same. One thing I'm not certain about is the front and rear glass...... I've never really looked into that so I don't know
the insides are almost identical, I don't know if the rear sail panels are interchangeable or if that rear glass is different or in a slightly different physical spot. I do know things like the seats, console, package tray, headliner, carpet and dash can be changed over....