I think it was originally a 400. I looked the VIN up once and found that it was silver with a black vinyl top, had AC, and I think it was a 400. I'll have to look again. I think that very little of the mechanical stuff was left when I got it. The current engine is a 1975 455 with 6X heads (from a 1973 350 from a GTO (I think)). All I'm 100% sure of is that the old engine was a 350 (stamped on the old block). The whole saga with this car has been bittersweet (but mostly sweet). I was looking for a musclecar, preferably a 1969 Camaro, but I couldn't find anything solid that I could afford. I alsmot bought a 1996 Camaro, but at the last second I saw this in the local newspaper for $4200. The car was in California until around 1998 (so the body's fairly solid), then it came to Wisconsin, and then Dubuque, IA where I bought it. It came with a 4:11 rear gear and a bit of a tired engine. The engine only lasted about a week as I was going about 80-85 down the highway and she spun a rod bearing. I was initially pretty bummed, but then excited because I got to put in a 455 I found a block for $550 and put the whole engine together for only about $1200. It supposedly had around 340 horsepower and 460 ft-lb (dyno sim from some Pontiac website), which I thought was pretty good for the little amount of money I had in the engine. I drove it a few times a month during the nice months until around this time in 2006. I was driving her home and the oil pressure gauge dropped to 0. I pulled over right away and had it hauled home. I thought there was something seriously wrong and I didn't have the money to fix anything, so I parked it for a year. I decided to start it up last fall (2007), and the oil pressure was normal again! Maybe a loose connection in the gauge? Bummer. So I drove it a few times, but it was leaking oil, which concerned me. It turned out to be a leaking drain plug (stripped out). I got an oversized plug around May 2008 and drove it for about 5 minutes before it made an awful knocking noise. Turns out a rod bolt broke or stretched and broke the rod cap and cracked a piston. So I took the engine to the machine shop in early June this year, told him to build the bottom end to be able to withstand at least 650 hp (for when I get my nice new heads) and got it back earlier this month...I guess Pontiac rods and pistons are hard to come by these days, at least according to the guy I took it to! Anyway, needless to say I don't want the same thing to happen again. The shop guy blamed it on "peanut butter" stock Pontiac rods (meaning they suck). The engine is running about the same as it did back then, heating up to around 230 when driving down the highway, and then pinging when it gets warm. I'm not sure if that could contribute to the rod bolt/cap breaking or not, but I don't want to take any chances. I also got a nice new 7 qt Moroso oil pan during the rebuild...$230 for those suckers! Once I get this engine straightened out I only need bodywork, new carpet, air shocks, exhaust, etc...haha. I never realized how much time and money these old cars take, but it sure is worth it when you're behind the wheel! Sorry for writing a book.