this may be a dumb question... but i hear alot about codes, C codes, K codes ect... first off what is the difference in the codes and how do i figure out what code my 69 coupe is

 

These are engine codes and can be found on your vin. For example a 1964.5-1967 (68?) might have a 289 4v HIPO solid lifer engine shown as a'K' code identifer on the vin.

I believe your '69 options are:
T - 200 ci 1V 6-cyl. with 115hp
L - 250 ci 1V V-6 with 155hp
F - 302 ci 2V V-8 with 220hp
G - 302 ci 4V V-8 with 290hp (BOSS 302)
H - 351 ci 2V V-8 with 250hp
M - 351 ci 4V V-8 with 290hp
S - 390 ci 4V V-8 with 320hp
Q - 428 ci 4V V-8 with 335hp (COBRA JET)
R - 428 ci 4V V-8 with 335hp (COBRA JET-R)
Z - 429 ci 4V V-8 with 375hp (BOSS 429)

 

Yeah, by the time 1969 came around, the engine codes changed. The early Mustangs had T, D, C, A and K codes. The T was the 6 banger, the D was the low compression 289, then in August of 1964 the 65 C code 2 barrel carbed models came out with the 9.3 compresssion 289 along with the A code 10:1 compression ratio 4 barrel carbed model. The K code was the hottest engine for the early models, and it came out in June of 1964.

 

well.... i have a 302 mexican block... does that make a difference in codes

 

No, but the Hecho en Mexico block is stronger because of the added nickel content in the metal.