I have been wanting to post this for the last couple weeks and never seem to get the time. I will try to keep it short to get the ball rolling and apologize in advance because I am sure a lot has been covered. I HAVE searched and read a bit by the way!

The short of it is I have an 86 GT fastback and available to me a complete 2004 Grand Prix GTP Comp G. I understand first off it is easiest to convert to cable throttle and I believe 99-03 GTP electronics/computer to control it. I also believe it needs to be a 2003 GTP computer if I want to run the automatic transmission that is already bolted to the 3.8 SC in the donor car. This brings me to the next question.

If I do this swap, I want to do it the cheapest and easiest I can to get it back driving and little down time. I am not against using the automatic but would really rather keep the car standard shift (believe it is a M17 code 4 speed in it now) I understand it may not hold up if beat on or anyways with 177k miles but I could possibly upgrade to a 5 or 6 speed in the future. I think I read somewhere I would need a special or maybe even custom flywheel/clutch setup to use the Grand Prix 3800 SC with the factory 4 speed. I thought I found a member/vendor on here but cant remember who or how long ago the post was. Next question!

How available are the needed parts anymore? Is anyone on here or any source still producing items such as mounts, wiring, tuning, etc? I believe the most time consuming and involved part of the swap from what I am reading would probably be the wiring/tuning and the exhaust. Its looking like a mostly stock budget build can make due on the factory 3.8 SC manifolds then a little custom work and bends to get down and out the rear. I am going to try to read up on this more this weekend. I would love to be told that I could still buy mounts, pre made harnesses, and an out of the box tune to get it driving at least, if possible!

I am sure more questions to come! Thanks in advance for any help. I feel I am in the right place for it!

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1986 Fiero GT
2.8 V6 4 Speed
176k+ Miles

I got some time to do some searching today and plan to try to contact Fierorog to get started figuring out the mounting and flywheel end of things. I know the information is all here if I can find the time to search for and read it. Then I just have to make my own specific list out of it!

quote Originally posted by UP86GT: I got some time to do some searching today and plan to try to contact Fierorog to get started figuring out the mounting and flywheel end of things. I know the information is all here if I can find the time to search for and read it. Then I just have to make my own specific list out of it!

You might want to check out this 'budget' swap for ideas. There are a ton of threads on the 3.8SC swap. Project Genisis Lo Budget 3800SC

[This message has been edited by Notorio (edited 06-25-2022).]

If you go with the cable operated throttle body, you are correct the 2003 PCM is the only one that will shift the 03-07 4T65eHD transmissions . Beyond that you will need a 2003 GTP harness the 03 MAF, TB and the power center if you wish to use the quick and easy wiring. As an alternative you could buy an adapter and use a N* TB and an early Camaro MAF sensor but that will require reprogramming the computer so that it can work with those changes. The rest is just mounting and Fierorog can help you with that. A low mount alternator is recommended and I believe that Fierorog has that bracket as well. You can leave the alternator in the stock location but that would require notching the deck lid bracket that I do not recommend. Check out Austins 3800SC build thread as there is some excellent info there.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

I build wiring harnesses for that application, and can arrange PCM programming as well.

Thank you Notorio and Dennis for the info and link. Olejoedad I pm’d you. (I believe) I talked to Fierorog and he still makes the parts and I should be looking at a little over $600 for everything needed from him. I think that was for the mounts, flywheel, alt bracket kit and dogbone. I should of had a pen and paper handy.. I do want to use the GTP parts if I can find them if it makes the wiring/tuning easier!

Thanks again guys!

[This message has been edited by UP86GT (edited 06-28-2022).]

quote Originally posted by Dennis LaGrua: If you go with the cable operated throttle body, you are correct the 2003 PCM is the only one that will shift the 03-07 4T65eHD transmissions . Beyond that you will need a 2003 GTP harness the 03 MAF, TB and the power center if you wish to use the quick and easy wiring. As an alternative you could buy an adapter and use a N* TB and an early Camaro MAF sensor but that will require reprogramming the computer so that it can work with those changes. The rest is just mounting and Fierorog can help you with that. A low mount alternator is recommended and I believe that Fierorog has that bracket as well. You can leave the alternator in the stock location but that would require notching the deck lid bracket that I do not recommend. Check out Austins 3800SC build thread as there is some excellent info there.

Dennis, what is the “power center” you are referring to? Also if going standard can I use any 99-03 harness/PCM/TB?

Thanks again!