Thinking of going wild 3.4, 3.5, or 3.9???

[Jonpro03]

Oh, and you have to drill and tap the oil pan for the oil return from the turbo. Im not sure where to get coolant for the turbo either, but I'd imagine the 3500 has coolant lines to the throttle body, so you could prolly use those.

If I think of anything else Ill let you know.

[TGed]

You can use a 3400 TB or short star TB with an adapter.  Those TB's have provisions for IAC, TPS and vacuum ports, I used a 3400 TB since I really didn't see the need for a bigger TB.  A bigger TB just asks for tougher driveability when tuning comes about.  I suggest a quad TB box and cables also.  Makes things simpler.  It's what I used. 
The ex-manifolds CAN be used, but IF you can make some logs or shorties, it wouldn't be a bad idea.  You wouldn't gain much if anything by doing so, it would just look slightly better assuming you can fabricate well and make nice welds.  The lx5 exhaust manifolds act as shorty headers as it is and a downpipe is only required to tie it all in.  IF you made or bought full length headers, that would be best for performance, but the cost to power ratio is very far apart.  I cannot see spending 300+ for 25hp and have to modify engine bay components to make them fit.
You will need different injectors, the lx9 just will out flow stock injectors very quickly.  28lbers are what I suggest for 350hp.  Also, you will need a 3100/3400 fuel rail and a pre 1999 FPR. 
The rear trans to engine block mounting WILL need to be addressed.  Some holes don't line up and you will need to attention that like I had to.  Some test fitting and scribes worked out well.
The front radiator dog bone mount will need to be remade.  You cannot use the stock one from either configuration and you cannot modify it enough to fit.  You will need to make one from scratch.  You could swap subframes with another year GP (GTP 94-96) and use the 94-96 GP 3100 mounting for the timing cover engine cradle mount and the one dog bone style mount on the drivers side.  You cannot use the stock GTP 94-96 timing cover mount since the crank trigger bracket will not bolt of correctly.  You must use the 3100/3400 W body mounting.

Have fun!  I know I did!

[GPChief]

My evolution......still in progress :icon_cool:  I currently have the 3500 UIM with the adapter for a modified 3400 TB.  

Notes from my experience:
- The "ears" on the 3100 / 3400 UIM are weak and I have broken 2! (thats why I went with the 3500 UIM)
- If you use a 3100 make sure youget the "big bore" version (same as the 3400)
- When you match the exhaust manifold - I thought it was the best practice to make the ports into the "D" shape to match. - use carbide tools :icon_wink:
- You will need to lengthen several sets of wires.  If I ever did it again I would replace ALL weather pac connectors on the wiring harness I think 3/4 of my locking tabs are broken and "zip tied" on now.

[Jonpro03]

I thought that 3500 used the same engine mounts as any other 3x00. Do we have to do a cradle swap? Or can we just use the 3100 timing chain cover and mount?
As for upper engine mounts? Could I just drill and tap holes? I don't have a problem using 1 mount

[Shifter23]

Hmm... all good info to know considering what we might get into we might have to go 3400 after all.  That or 3400 hybrid with 3500 intake parts.   It sounds like a good deal that way from what I have found and heard.

[mfewtrail]

I thought that 3500 used the same engine mounts as any other 3x00. Do we have to do a cradle swap? Or can we just use the 3100 timing chain cover and mount?
As for upper engine mounts? Could I just drill and tap holes? I don't have a problem using 1 mount

There's someone that has 3500 swapped into a w-body. He has a thread on w-body.com and 60degree from what I remember that should cover most of what has to be done. He goes by "PCGUY112887."

[killinprixs]

Hey GPCheif, do you have a closeup of your throttle linkage?  you using the original throttle cable?  Mine is pissin me off and i might have to get a newer style cable.

[GPChief]

You need the newer throttle cable.  am also trying to come up with a good solution for attaching the kick down cable and (eventually cruise control).  Am trying to see if I can take the TB arm from an outher TB that has metal mounts.

[killinprixs]

Thanks for the info, gonna have to grab newer style, the old cable setup sticks at wot!  Let me know if you find the right throttle plate, it sure would be nice to use an OE part than a fabbed template, thats the only cob job id like to take care of before swappin it in the 5 speed.

[TGed]

The TGP cradle should work, but you will need all the brackets as mentioned prior to complete the swap and some possible mount making.