I bought a rolling SS396 Elco. I got it into the shop today and pulled the front clip. It has a single 3/8" fuel line, so I started sandblasting the firewall. I found what looks like a "78". (I didn't have to time to go further) The car is an automatic, which seems to be some debate about 68 L78/TH400 combos. It came with a tach cluster(not installed) with the 325/350 redline. It also is a column shift auto, and a bench seat cowl tag code. Is it possible to have the L78/TH400 combo? Its has a 12/67 build date.

Is the model number on the cowl tag and VIN (1st 5 digits) 13880?

No L78 engine codes with TH400 in 1968, 1969+ yes.

If the car has factory A/C, that would rule out any L78. NOT available with A/C

As Mike said the general consensus is No L78 automatic Chevelles in 1968.

Still a great car.Sounds like mine and same builddate era.Mines bench,T400,auto on the column,tach,and am/fm.Added the tilt steering.Great car just bad design on the column shift indicator.The cable likes to saw into the plastic after awhile.

Its a 13880 car, no A/C. It has some insulation on the floor that I have to pull, so I am not sure if it was a 4sp car originally. The steering column may have been changed, because it has a non-BB intermediate shaft on it. Were the engine codes written on the firewall on the Freemont cars? The "78" is written above the heater core area. I haven't blasted farther to the right to see if there is a "L".

I don't think the assembly plant would know the option code L78, they used suffix codes to id engines, There are several possible L78 engine configurations to use and L78 would not tell them much. All the engines would be labeled with the engine suffix code and staged for installation into the vehicel long before the chassis met up with the body in marriage.

78 could also refer to many things, I see 3 interior colors 78x, could be the sequence number of the car.