On my 78 F250 400 , it looks like the numbers on the block are 7C3O andmd D7TE-A3B. My question is, does this number mean that the original block was replaced? Or, did the factory put 77 blocks in 78 model year pickups. I may be over thinking this.

Thanks.

 

March 30 '77. I've read here that they let the blocks sit for a while after casting. If that is the case here, then your March block would have been about right for an early production '78.

D7TE is the revision date for the casting and appears to have carried on to the end of 400 production if I am reading this right:

Kelly hotrod - Ford Engines Page 2

Nothing to worry about.

 

It is the engineering revision number for the block mold.

THey were not changed every year to match production.

It's normal.

 

D7TE-A3B = Block casting number for 351M/400: 1977/79 F100/350 & 1978/79 Bronco.

7C30 = Block cast March (C) 30, 1977 (7).

Once the block was cast, it sat outside to 'season' then was shipped to the engine assembly plant to be finished, then was sent to an assembly plant to be installed in a vehicle.

This process could take between 6 months to a year.