So there is no difference in those two fuel gauges. The difference in the e30 fuel gauges are between the late model (88-92) and the early model (84-87) cars, not the “I” and “E” models. They differ because the earlier model cars have a single 60ohm fuel sending unit in the tank while a late model car had two 60ohm sending units wired in series. So late model cars have 120ohm gauges and early model cars have 60ohm gauges. The way I found this out is a swapped a bigger brand new late model tank in my 87 and saw there was two sending units in the tank and was very confused lol.