There's a thread on this, fairly recent too. Had a lot of info. Found it: http://www.jalopyjournal.com/forum/threads/how-do-i-tell-the-difference-between-a-348-or-409.999092/
After a little more research it would appear that aside from internal inspection, decyphering the casting numbers at back of the block is the best bet. Right now all I have to go by a couple small grainy pictures. I see what looks like a cast iron intake with four barrel and dip stick on driver side. Truck has 4 speed transmission, looks relatively clean and is said to run and drive very good. But priced too high to fit description unless the engine was something special.
The truck 348 had the dipstick on the passenger side. the best most certain way is to pull the heads and measure it.
Some of the truck engines had two relief cuts in the block and that to me would preclude using it for a hot rod because of the excessively low compression. You need to pull a head to be certain.
Can't use the dipstick idea because the 348 and 409 oil pans interchanged. Use the 348 site link and there is a section to plug in your casting code..
thanks for all the tips guys, I will try to get a first hand look at it in the next day or two, if it doesn't sell before then, and get some numbers off it. ...wonder if one of those fancy new fangled inspection cameras run down a plug hole would show if the bores had the low compression over-cut?..
The extra cut in the cylinder is an advantage with the right pistons, it unshroudes the exhaust vale for more performance! Gary
Been awhile had several of each but back in the 60's. Besides the dipstick I seem to remember that the intake bolts are "in-line" in 348's but center ones are staggered in 409's.
No, a standard performance 409 intake and a 348 intake will interchange. And the dipstick is in the oil pan and a 409 oilpan will bolt onto a 348. Only way I know to check externally is to look at the stamping on the front right hand side of the engine, or the casting numbers on the rear of the engine.
I need to make it clear that I am no expert on the subject but according to another thread on the 409 at the moment, the 348 has a bow rope attached and the 409 utilized an anchor chain. Hey, I don't make this stuff up, I just report it.
The water pumps are the same, and they started putting the X's on the blocks in late '62. It is a pretty good indicator that it may be '09, but not foolproof, as some 348" truck blocks had them also.
The "X" on the block was also put on truck blocks. I have one. Here is one other way to tell if you have a truck block, but only good for this one year. For the 1965 #3857656 block, look on the lower front of block on each side of the timing cover. On the left side (right side when standing in front of engine) there are two 7/16" coarse thread bolt holes which the power steering pump bolts to. These are drilled on all blocks both car and trucks however, truck blocks will also have these drilled and tapped on the right side of the block (left side when standing in front of engine) where passenger car blocks won't. No bolt holes on that side indicates a car block, with bolt holes indicates a truck block. No car blocks ever came from the factory with these drilled. Note however, someone other than the factory could drill and tap these so it's not proof positive.
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