I have a 71 Chevelle and in 99.9% sure its a true Heavy Chevy. But, I want to be 100% sure and also find out more about it, value, etc. How do I tell exactly if it is? It had the original paint on it when I bought it and it had the Heavy Chevy vinly stripe and lettering. And on the Build sheet it said "YF4" which I believe is the Heavy Chevy code. Any info would be much appreciated.

I think the Heavy Chevy code is "YF3". There is no YF4 code for a 71. If the build sheet has the correct code then you have a Heavy, congrats. Now lets see some pics!

You will get more info in the " whats it worth" section

All Heavy's were built on the 13437 platform, so first verify that on your trim tag (ST-13437).
YF3 is the RPO code for Heavy Chevy, not YF4.
BillL

YF4 shows as 'Sales Promotion' and no I haven't a clue what that means.
See if Dale knows ,it's from his site.
http://www.chevellestuff.com/qd/rpo2.htm

According to the "Models thru 1975" parts catalog;

YF4 - BUMPER GUARD AND BUMPER STRIP

Sorry i meant to sat "YF3", Does anyone know how many of these were built in 71?

All Heavy's were built on the 13437 platform, so first verify that on your trim tag (ST-13437).
YF3 is the RPO code for Heavy Chevy, not YF4.
BillL

And yes, the first digits in the vin are 13437!

Sorry i meant to sat "YF3", Does anyone know how many of these were built in 71?

http://www.chevellestuff.com/1971/options_by_model.htm

I have a 71 Chevelle and in 99.9% sure its a true Heavy Chevy. But, I want to be 100% sure and also find out more about it, value, etc. How do I tell exactly if it is? It had the original paint on it when I bought it and it had the Heavy Chevy vinly stripe and lettering. And on the Build sheet it said "YF4" which I believe is the Heavy Chevy code. Any info would be much appreciated.

So...did you ever figure out if you have a True Heavy?