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Thank you thank you for yours and everyone’s help. It is greatly appreciated. I had no idea there was a Facebook tgp group. I will be checking that out thoroughly. Anyway here’s a picture of my old Grand Prix. It was the reason I even knew about the tgp. I thought I knew everything about gp’s at one time. But I didn’t and still don’t. 69 sj I still regret selling it.

You're actually the 2nd newb to inquire about the 90 degree swap in as many days, Mattmac2007 recently did an L67 swap into a 1st Gen GTP earlier this year, he more than likely would be the freshest source for info on what has to be done. He did a thread on the conversion.....

Once this swap is done as the motor n tranny I have are in very good shape. I would love to get looking into the 3500 swap I have 2 1993 luminas so ones staying a daily till the swaps done then id love to get a ton of info on how to do and how easy that 3500 swap is thanks.

Either engine swap you do, you will need different harness, with 3.5 or l67 with 4t65hd trans. Easy way is to spend $200 get then harness and OBDII from Miltzy.

Easiest way is to convert it to OBD2... L67SS has done this, but on a 96 or 97 Monte Carlo. Converting to OBD2 isn't bad if you know what you;re doing, it's mostly repinning stuff. You SHOULD swap out the trans because of the gearing ratio, not to mention the 4T60E is a twig compared to the 4T65E-HD. You want a 65 HD in there mated to the L67, unless you wanna do a manual swap, which I THINK that the F40 from the G6 works. You could also get a non VVT 3.5 from a G6 but idk how much more work you have to do, I just know that the 3500 replaced the 3100 and 3400, which themselves replaced the 3.1 mpfi. The 3.4 was an oddball engine, nothing preceded it nor succeeded it.

Definately the 3400 SC'd.. Then dont do up the outside.. Keep it a very plain jane looking car, and race for ownership! ROFL.. jk.. But definately an 00+ 3100, or a 3400 swap SC'd would own.. Im doin a 3100 top end on a 3.1 MPFI block, and Im turboing it