I'm trying to determine if the engine in my 1969 Mustang Mach I is original/numbers matching for the car. The engine block shows the following sequence of numbers: C90E-6015-B, as well as 9B27. It was produced with a 351V-4 Windsor. Can anyone help me? Thanks!

 

I think you need to correlate the build dates...there is not real 'numbers matching' like some other makes, IIRC.

 

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that is feb 27 1969 . . it was actually assembled after that . . the assembly date is on the right front of the block head surface on a small tab just in front of the cyl head.

this date must precede the build date of your car by 1 to 6 weeks.