If it's a 4x4 and the original engine, it should be a 360, and have a 2V carb- the 390 was not available in the later 4x4's, only the 360 and the 300 6 cylinder. What are the complete casting #'s and date codes on the heads? 360 and 390 pickup engines of the same year would generally have the same heads, yours would have probably come with the D2TE-AA ('72 and up) castings and have the hardened exhaust seats in '76- if they've been swapped out for "rebuilt" heads, they could be anything, and wouldn't help ID'ing anything except themselves. Look at the crank, you should find a casting ID cast in one of the counterweights, 2T is 360, 2U is 390 for later years ('68-up). It'll be on the narrow edge of a CW, not on the face- keep looking, you'll find it (too cold to walk out to the shop and see which CW it's on- sorry )

 

Hey i looked on the crank the only thing i see is 23 and 3. thats it. i saw some harmonic balncer numbers would that help

 

To repeat an old post - the difference between a 360 and a 390 was the rotating assembly. Some have said a 360 was a de-stroked 390. Get a 390 and put in 360 pistons and you might end up with a 390 (basic) Cobra.

 

Have us "Old Guys" confused you yet? There were so many variations of the FE that we all get confused at times.
For a 4X4 application that will be used for recreation The 360 engine is a good choice. If it's going to see a lot of off road/trail use I would keep it nearly stock with the exception of an RV grind cam and kit. Don't try to make a race truck out of it as the outflow of ca$h will never stop.

 

Alright thanks. I found the crank number it is 2ta its a 360 crank.I got a question ? i pulled the motor and it was covered in slug i am getting new pistons and everthing should i get it just cleaned or bored over like .10? Also i got a 360 crank if i wanted to put a 390 on it what all would i have to do to it?

 

The 390 uses a different crank and rods (shorter, hence stronger). Depending on how much compression you want, you might be able to use the 360 pistons. As to cleaning the block, always have the block tanked. As to the need for a bore job. Your machine shop will have to check the bores for wear, out of roundness and taper and will be able to tell you if the block needs boring. FYI I do not believe there are any .010 over sized pistons for any engine. .015 is about the minimum you can go.

 

What he said.

 

Sounds like Jeff is used to motorcycle engines, where .010 is the norm for a first overbore, leaving plenty of sleeve for .020, .030 etc. A .030, unfortunately, is probably the smallest commonly available piston for a 390- a shame, because the blocks would usually clean up at .010, unless very worn or scratched. When you go to a custom size, the only limitation is available ring sizes- and that's helped by the +.005 hand-fit sizes. I'm doing a customer 428CJ/ 450 stroker, and it had already had the old .030 number done on it, and was scratched up some from some broken top rings, so it was power-honed and cleaned up well on the CK-10 to 4.165 (+ .035) which is a common off the shelf ring size, and the pistons didn't cost any more as they were already customs for the stroker and long rods. No need to go to .040 or .060, and keeps the walls as thick as possible- the block was also concreted up to the freeze plugs to help out the walls a bit