Alright, I came across this Chevelle and it's a Chevelle Malibu. The emblem on the side of the car says 350. I thought the 350's weren't available until 1969, but people are saying it's a 68. Am I right or is it really a 68?
Check the VIN. It should read 137 for a Chevelle Malibu Sport, then either 37 or 57 for the 2 door hardtop, then the last number of the model year, ie 8 for 1968 or 9 for 1969, the next number is the assembly plant, and the last 8-13 digits are the sequential build numbers.
So the VIN should read something like this: 137578T007635
You can also check the cowl tag. The year will be right next to the letters "ST" located on the left. It will say either 68-xxxxx for 1968 or 69 for 1969.
As odium said you can check the VIN. 68 chevelles did not come with a 350, wasn't even an option. Only smallblocks offered with the chevelles that year were (I think) were 307 & 327, along with a 6cyl. and a 396. You could look at the grille and taillights too.