are 89 hf clusters the same as a 90-91 si cluster or are they interchangeable to??

 

there the same

 

88-89 plugs are set up differently compared to 90-91 plugs. they visually appear similar, however the wires are in different places and are NOT the same, and not plug-n-play. you'll have to get a pin-out and figure out which wires need to be moved around.

 

Also the hf cluster redlines lower than the si

 

the clusters are completly different 88-89 are the more square ones while the 90-91 are more rounded at the top..