roller rocker question

the 351 on the rockers does not mean they are 351 heads, the 351 on the rockers is merely part of a part number as in M-6564-E351...that's the part # for FRPP's non-adjustable 1.7 ratio rockers-unless you have vertical bars on the front and rear of the heads, they're probably stock...

...on the other hand if you tried to put stock plugs in and they didn't fit, you might have GT-40 heads-they use longer plugs than stock (AGSF32-I think)... the old 351 heads used the 13/16's socket spark plugs if I'm not mistaken, and new 351 heads would be a waste since after 1978, they were the same as what were put on 302's

when you take them off, look for a casting number under the intake runners, if you see E7TE on them, they're stock...if they're F3ZE, they're GT-40's, if F7TE, they're GT-40P's...

if you see something else, post it on here, or run a search, and you can find out what they are...