Hello All,

New here and to Fiero's. I recently purchased a Red 2 owner 1986 GT auto 208K on the clock but the engine runs nicely. I'd like to start planning for the 3800 SC II swap and was wondering what parts to pull off a donor car. I am looking at two 3800sc cars, First one is a 2004 Buick Park Avenue Ultra and the other is a 1996 Buick Riviera Supercharged are these cars recommended? Or should I target a different car? From what I have read so far I know I need the following. Motor, Trans, Axles, Harness and ECU. Any other parts?

Sorry if my next question sounds stupid.

To avoid having to mess with the Fiero's wiring into the existing harness. Could you not use the donors car's gauges to avoid the headaches?

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JM

There are threads answering this question, here is one: LINK. The gauges are not directly involved in the swap wiring, that wiring extends only as far as the C500 connector in the engine compartment of the Fiero, and to the C203 connector under the center console. You could use gauges from the donor car, but that would seem to increase the complexity of the build, not simplify it.

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1988 Pontiac Fiero Formula, Yellow, original. (CJB #118)
1977 Pontiac Le Mans Can-Am W72, original, unrestored.
1977 Pontiac Grand LeMans
2003 Pontiac Grand Prix GTP L67/MN7 (Parts Car)
2001 Pontiac Grand Prix GTP L67/MN7 (DD)
2005 Pontiac Grand Prix L26 (Wife's DD)

AC line, pressure senor, and sensor plug & cruise module and plug. I consider these necessities, but if you don't plan on using them you don't need them.

If you are going to move the battery up front, take the Riviera's battery cable ( from back seat). ON either the Riv or the Ultra, take the extra Relays that are attached to the firewall. Always come in handy. The Riviera has a unique engine harness arrangement, where it plugs into a connector on the firewall, which then connects to the ECM and the rest of the wiring. A little more complicated than say a Grand Prix harness, but still doable. When I did the Riviera, I wired the connectors to end where the Fiero Battery now sits. Makes it easy to take the engine out, but like I said the wiring to get there is more complicated. I took a lot of the rest of the wiring from the Riviera just to have wire to extend where necessary. The Riviera also has lots of parts for "part out" that might recover some of your money, if they are in good condition.

I found the Grand Prix harness the easiest to work with- It's nearly a direct plug in- just a few wires to connect to the Fiero ( I used the underhood Fuse box from the Grand Prix too- just took it all out as one assembly). The GP also has the correct front accessory drive, as well as the right Oil Filter adapter.

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SCREW PHOTOBUCKET. All my pictures are now available at https://www.flickr.com/photos/156871275@N07/albums
'87 GT , '00 3800 Series II SC, 4t65e, Vue Power Steering. (SOLD)

Looks like the Grand Prix is the way to go. I hope to find one soon.
Thank you all the reply and the help.