I am pretty sure the SI and HF harness's are the same off an 88-91 am I correct? I am just making sure. There is an HF harness at the junkyard, and my freind with a LS needs it, just making sure it will work. I tell him it will he says it wont.. Thanks.

 

HF and Si are slightly different. But the main difference is in the years. The 88 and 89 are different from each other and the 90-91 are the same.

 

they are pretty much the same. the only thing thats different about it is the hf has a EGR wire and the Si doesnt. I say just use the hf and forget about the EGR wire, just leave it hanging around or cut it off.