We receive many phone calls from classic Mustang enthusiasts inquiring if the engine in their 1969 or 1970 Mustang or the 1969 or 1970 Mustang they are contemplating purchasing is a 351 V-8 Windsor or a 351 V-8 Cleveland. First of all, virtually all 1969 351 V-8 engines were Windsors and virtually all 1970 351 V-8 engines were Clevelands. There are a few exceptions. Over the years we have seen a few 1969 Mustangs with factory installed Cleveland engines. By checking the build dates of these Cleveland 1969’s we found that in every case these Mustangs were produced in the last week or two of 1969 production when perhaps the factory ran out of Windsor engines. Conversely, we have also seen very early production 1970 Mustangs equipped with 351 V-8 Windsor engines. Again, perhaps the producing factory was using up their supply of Windsor engines before beginning Cleveland engine production. In either case we have found these to be very rare occurrences.
The 351 Windsor's radiator hose attaches to the radiator and connects directly to the front of the intake manifold via a water neck.
WINDSOR 351 V-8 ENGINE
Valve cover is held in place by 6 bolts.
Spark plug socket is 13/16 inch size.
Distributor gear is 1 1/4 inch diameter.
Radiator hose connects to water neck on the front of the intake manifold.
The 351 Cleveland's radiator hose attaches to the radiator and connects directly into the front of the engine block. It makes a 90° bend from the radiator to the engine block.
CLEVELAND 351 V-8 ENGINE
Valve cover is held in place by 8 bolts.
Spark plug socket is 5/8 inch size.
Distributor gear is 1 1/2 inch diameter.
Radiator hose is essentially a 90 degree hose that connects directly to the top front of the engine block.
CASTING NUMBERS
1969 351W engine block -- both 2 barrel and 4 barrel engines -- C8TE-6015-A
1970 351W engine block -- both 2 barrel and 4 barrel engines -- C90E-6015-A or C90E-6015-B or D
1970 351C engine block -- Before 10/15/70 --D0AE-6015-A, C, E, G, J
1970 351C engine block -- After 10/15/70 --D0AE-6015L
1970 351 V-8 Cleveland 4 barrel heads -- D0AE-G, M, N, or R
We hope that this information is helpful to you. Other than Boss 351 Cleveland engines, 351 V-8 Windsors and 351 V-8 Clevelands were not serial numbered to the car. They were date coded at the time they were cast. The date codes and casting numbers are typically located behind the starter. If an engine’s date code precedes the build date of the Mustang by no more than three months, it is generally accepted that it could be the original engine.
Again, we hope that you find this information helpful.
