block decode

[79cobra502lx0]

i have a new block for my 1979 ford mustang cobra and i think its either a 74 or a 84 block but I'm not sure the engine number is D4DE-6015-AA i would apreciate some help in identifying the blocks year thank you

[negusm]

D4=74

[negusm]

Well, to clarify...

Any Ford part starting in E4 would be 1984 and D9 would be 1979.
For parts start with a letter representing the decade:
C=60
D=70
E=80
F=90...

and the second number is the year.....

I always remember from C=60 since they sound similar...

-Mike

[FoxChassis]

D4DE-6015-AA is a Service Part Number, aka a "casting number", and it DOES NOT tell you what year the part was manufactured (if that's what the question was). It only tells you what year the original design was released for service. Yes, D4 = 1974, so all that means is the block in question was released for service in 1974, not necessarily manufactured in 1974. If you want to know what year the part was manufactured, you need the Date Code, which, on "Windsor family" small blocks, is in the same area as the Service Part Number.

For a full explanation of Service Part Numbers and Date Codes, and what they decode to, you may peruse the following topics I authored at the 1982-1993 Mustang GT Registry (http://www.mustanggt.org).

Service Part Number deciphering (http://www.mustanggt.org/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=10;t=000276)
Date Code deciphering (http://www.mustanggt.org/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=10;t=000277)

[negusm]

Ahh yes, what he said... :oops:

-Mike