Hmmm, It's been a long time since Ive jumped into one of these discussions but I still have a thing for the 409 club so I'm back in for this thread and Ill try to answer your question. If the car that you're asking about happens to be a black convertible with white top in Alabama for $75K dont wate your time or money. The car is bogus. The dealer that has it, knows it too. As they ALL DO !!!!!!
OK, so let's get serious. First, what ORIGINAL documentation does the seller or salesman offer to show you??? Sales brochures and 1965 owners manuals are neat but they are also a dime a dozen on ebay and are in reproduction. Does the seller have the original protection plan booklet with protecto plate?? If so, write everything you see down then do your research. There are books (also on ebay) that tell you how to decode Chevy protecto plates 1965-72 Does the seller have a collection of receipts that date back before like the last three years??? If so, look at them. Does the name of the person making the repair on the receipt match the name printed in the protection plan booklette?? Often you'll even see 409 engine appear in repair or tune-up receipts of days gone by.
The VIN will tell you what it is. Impala or Impala SS or whatever big car it happens to be. The VIN decoder on this website is a handy tool that you should take some time to look at it. Bob the Administrator spent quite a bit of time getting all of that data straightened out.
A '65 Impala convertible with V-8 engine VIN will be a 16467 a 5 then a letter which designates the build plant, then serial number
Data tag is the next thing that you should look at. Upper left corner will tell you the month and week when it was built. It will also tell you what color it was, what interior it had, in the case of a convertible car what color top it came with , and the accessories it came with.
Again Bob's data tag information is another real handy tool. If your'e looking at a 4-speed car just rember that a M code data tag is Powerglide, L is 4-speed and A is TH-400. If you see an A code with a 409, there's a problem. 409 never came with TH-400 trans. When looking at any '65 "W" car that build date better not extend beyond 03D if it's a St. Louis car, or 02D anywhere else. If it does, the car did not come orignally equipped with 409 engine.
Besides the usual stuff like 12 bolt rear 4-link rear suspension, twin fuel lines and so on, write down ALL of the casting numbers and date codes of everything that you can find. Block and heads especially. Now many sales people WILL NOT WANT to pull a V/C for you so that you can look. Take a new pair of W v/c gaskets with you as an offering. If you are refused, walk away. 6 bolts and a 7/16 nut driver is not a major deal by anybody's standard. If the heads arent 817s or 583s then why not??? How about the casting date codes on them, are they close to the block??? The block cannot be 6-months separated from the heads as far as that goes. Trans, and rear both have dating information on them too . In other words, does the whole thing jive ?!?!
Now onto the BIG 1965 secret that not many of these dealers know. All '65 W engines are 656 blocks. OK, so now the big question is how do you tell a truck block from a passenger car block from the outside ??? Look at the front of the block near the fuel pump. You will see a round pad for what looks like a stud boss. If you see a 7/16*14 tapped hole in that place it's a truck or post '65 replacement or agricultural/marine block. If it is solid cast iron, meaning no tapped hole, it's a passenger car block. Big truck engine mounts in '65 bolt to the front of the block, not the sides like that cars do.
Ill conclude with this, everyone has a story, every problem or discrepancy you discover will be met with an excuse. It's your money and let the car speak for itself!
Rock