Don't know if you know, but the 351C was not originally avialable in 69. Became an option shortly after 70 production started. None the less, it was a popular swap from what I am told. How to tell a 351C from a 351W. 351C heads will have 8 bolts in the valve covers instead of 6. (It is possible to put 351C heads on a 351W, this modification is generally known as a clevor) The neck of the thermostat housing comes out the top of the block and points straight up for the 351C while the 351W has a housing that comes out the front of the block. After you see a few it gets easy to tell them apart.
There is certinally nothing wrong with the 351C. During the 70's and early 80's they were the hot ticket in small block proformance with high flowing heads. However, the advent of fuel injection and computer aided design turned the 351W into a great proformer. Today you can make good power with either combo. Reliabiliy probably goes to the 351W but it isn't a really big deal. The biggest problem I see with the 351C is that aftermarket proformance parts are now more prevelant for the 351W. Now before someone jumps me on this, edelbrock and others offer more for the W, FMS has more W stuff, and when was the last time you saw readily available alum. heads and fuel injection for a 351C. But they are fun and of course all the old timers will ask you which engine you have and hope to hear 351C.
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