I have an 86 SE 4 speed that I had a wiring harness built for for my 3800SC Swap.
I now have the opportunity to buy a pristine 88 that I would put my 3800 in instead.

Are there any differences in the 88 wiring where I would need to change my wiring harness?

I know I will need different engine mounts.
Obviously the suspension is different.

Any other noteworthy changes for the 88s that I should know before I purchase it? Went and looked at it today, looks like a fair deal.
Link is here, seller is a member on PFF. Asking price is $2,000, motor will need to be removed.

I will be swapping the body panels from my aero 86 SE onto this formula if I buy it. Then the 86 will be up for sale, either wholesale or for parts, along with the formula body panels.
Welcome to all thoughts and ideas and comments.

Another Formula lost I guess.... It seems like what you want to do will work. Your car will have one horn, and no shift light......if that matters..

quote Originally posted by Gall757: Another Formula lost I guess.... It seems like what you want to do will work. Your car will have one horn, and no shift light......if that matters..

Do you mean another formula lost due to the body panel switch? Its unfortunate but my aero panels look better and are in better shape overall.

I would be removing the shift light and re-purposing it anyway, and my 86 already only has 1 horn because I switched to the 2nd gen headlights
Thanks

The backup lights wiring is different, the 4 speed b/u switch is in console attached to shifter. 88, if manual or auto, would be on transmission.

quote Originally posted by olejoedad: The backup lights wiring is different, the 4 speed b/u switch is in console attached to shifter. 88, if manual or auto, would be on transmission.

Is that the only difference?

88 V-6 cruise control is same as earlier years, but 87-88 four cylinder cars use the ECM for cruise function. Wiring is different in the interior.

quote Originally posted by olejoedad: The backup lights wiring is different, the 4 speed b/u switch is in console attached to shifter. 88, if manual or auto, would be on transmission.

The 86 wiring was equipped with provisions for either the 4 speed or the 5 speed manual.
The engine harness should have the socket for the B/U light switch, even if it's in a 4 speed car.
As the story goes, GM didn't know when the 4 speed to 5 speed changeover would happen, so the harnesses were manufactured to accommodate both.
All of the 4 cylinder cars also had the B/U light switch on the trans.

I'm guessing your harness will be plug and play.
There might be some difference in the alternator wiring (specifically, in the gauge and the light) since the 88 had a CS alternator, where the 86 had the SI. I'm not certain about that, however. If the system doesn't charge, you know where to start looking.

quote Originally posted by Gall757: Another Formula lost I guess....

Actually, this car was lost...The original owner started with a pristine low mileage car. And then proceeded to run it into the ground, it's been sitting for almost 3 yrs unloved.. And is now a ghost of it's former self. Kyle is going to bring it back to the way it should be, just with a little more gusto. I applaud him for doing this. -Jason

quote Originally posted by Raydar: The 86 wiring was equipped with provisions for either the 4 speed or the 5 speed manual. The engine harness should have the socket for the B/U light switch, even if it's in a 4 speed car. As the story goes, GM didn't know when the 4 speed to 5 speed changeover would happen, so the harnesses were manufactured to accommodate both. All of the 4 cylinder cars also had the B/U light switch on the trans. I'm guessing your harness will be plug and play. There might be some difference in the alternator wiring (specifically, in the gauge and the light) since the 88 had a CS alternator, where the 86 had the SI. I'm not certain about that, however. If the system doesn't charge, you know where to start looking.

Correct! Thanks for reminding me!

Seems like there was one other minor thing I ran into. At the C500, there was a change on the pinning for the ground and the fan relay signal. Early harness in an '88 will give you no tailiights (no ground to them) and a constantly running fan - signal wire grounded. Easy to fix - sorry, can;t remember the pinout - going from memory.

Mike