Vin should be "P" for LT-1, "W" for L-99 IIRC, true dual exhaust, both external coolers, LT-1 on SPID sticker in trunk are the most obvious. LT-1 should have GU4(3.08) rearend indicated on the SPID sticker as well. Try to find a G80 Posi also. Major power difference. If it gets down to an argument, the number 327 is stamped on the block of the LT-1's. Good luck.