here's the breakdown:
93 = first year. rocker sill plates have "Mark VIII" embossed. Seats do not have Lincoln emblem sewn in to the backrests. No center arm rest for back seat. 1 piece driveshaft. Intake air tube has small indentations on engine.
JBL amp and speakers are 93-94 model year ONLY and will produce better sound than 95-later. More aggressive ECU programming than 94+ years.
94 = Lincoln emblems sewn in to seat back rests. Smoothed intake air tube on engine. Revised door sill plates with nomenclature removed. 2 piece driveshaft replaced solid 1 piece. Simulated wood grain console and dash features added.
95 = known problem with poor valve springs on engine. many cylinder heads replaced under warranty. painted 10-spoke directional wheels were added as a standard wheel. Din 1/2 stereo. folding arm rest in back seat added. Homelink buttons added to sunvisor. exhaust tips added with rear bumper cut-outs. JBL system revised and sound quality declined.
* 95 1/2 = LSC model added to line up = LSC features = Perforated seat inserts, Mono-chrome body moldings/bumpers, 3.27;1 gear ratio, true dual exhaust (10hp increase) some models received HID headlamps.
96 = first year of OBD-II electronics. "diamond anniversary" special feature model introduced (one-year only) with two-tone seats, door panels and floormats features and etched rear quarter glass with "Diamond Anniversary". Some engine changes (mechanical) including IMRC actuators. "bee-hive" valve springs were added to engine internals to eliminate the 1995 valve spring problem. Transmission pan was revised. All LSC models received HID headlamps. Monochromatic body moldings continued from 95.
1997 = new body style changes, HID headlights and perforated seat inserts standard on all models. Interior trim changes, puddle lamps and turn signal LED'S added to side mirrors, rear trunk lighting(neon), aluminum hood instead of composite hood found on all gen 1's(93-96). Upgraded emission devices and re-designed engine intake manifold and secondary air injection added. "COP" (COIL-ON-PLUG) ignition system was added along with re-designed valve covers. Front air spring design was updated from metal to plastic. base models had standard chrome exterior trim front, side and rear. LSC models had monochromatic body trim front side and rear. Some late models received minor transmission components upgrades. Radio antenna removed from body and integrated in rear window glass.
1998 = final production year. Transmission received much-needed internal upgrades. many "limited production" models were added as production came to an end.
summary: all gen 1 exterior body panels are interchangeable. 93-94 center consoles are unique. 95-96 consoles are interchangeable. 1996 model year had many electronics upgrades with the OBD-II introduction. all 97-98 interior and exterior parts are interchangeable.
many model years had unique colors that were only available for that model year.
Diamond anniversary - 1996 only
Spring Feature = 1998 only
Collector's Edition = 1998 only
the "LSC" model was introduced in mid 1995 Production, although all mark VIII warranty cards referred to the car as a LSC
---I am sure I missed a few things as I am aging, so feel free to add them or correct me folks.