I picked up my dad's old farm truck for my oldest boy.  I don't know why, but he wanted it.  It hasn't seen pavement in years.   Didn't run.  I hauled it from Arkansas to Texas over the weekend and am now getting started.  Battery was shot so I replaced it.  After a shot of starter fluid and some fresh gas, it started right up.  It idles great..

But.....it smokes like a freight train out of the driver's side exhaust.  I checked fluids.  Oil was fresh but overfilled.  Trans fluid was super low.  I put in 2 quarts but still needs one or 2 more.  I replaced the vacuum modulator.  Tranny won't go into any gear but park.  
I plan on fixing the fluid levels today.  Any other thoughts on possible fixes?

Stuck oil rings or valve seals shot. Or, just worn out. Miles?

Transmission, fill to full, if doesn't do anything, check linkage. If OK, time to rip er apart.

Nice torquey at lower RPM engines for trucks. Strong as heck, parts availability, iffy. I had a 72 camper special pick up with a 390 back in 87 or so, damn good wood hauler, part even then were pricey compared to more common and plentiful engines.

Random thoughts, I’ve been playing with FE’s since the 60’s, I have 3 right now, 2 are in cars making in excess of 500 hp each.

I think it’s great that your son is interested!!

If the trans modulator was bad, it could have been sucking tranny fluid into the intake manifold, causing the smoking. I know you replaced it, but leave it disconnected at the intake and plug the vacuum connection while troubleshooting the engine and trans separately.

Stuck oil rings have already been mentioned. They might loosen up with time, or not, if they are really gunked up.

When the engine is idling, after up to normal operating temps, pull the oil filler cap and check for blow by. That will tell you a lot about the condition of the compression rings.

Valve stem seals may be cracked and rotten, they can be replaced without removing the heads, it is a slow and time consuming process, but it can be done. If the valve stem guides are bad, you’ll have to pull the heads.

The FE’s in pickup trucks were lower compression than the FE’s in cars of that era, due to piston deck height. Parts are still available, they just cost more and you may have to wait for your local parts store to get them. Performance parts for FE’s are probably more available now than they were when I was racing them in the 60’s, but they are pricey. Look to Summit or Jeg’s for stock or performance parts. Most guys at O’Reilly’s, Auto Zone, etc won’t know very much about FE’s except what the computer tells them, unless you find an old guy or a FE fan. Just Google “Ford FE” for lots of internet FE forums.

Best wishes with your project!  Good times for you and your son working together!

Looks like you might wanna start building a list of things to order from Rockauto...

https://www.rockauto.com/en/catalog/ford,1975,f-250,6.4l+390cid+v8,1122950

When you pull the oil cap to check for blowby, check for vacuum there as well.

How bad is bad for blowby?

Pull the plugs on the drivers side and look for the oil soaked one. Will help you narrow down where it’s coming from.

Ask dad if it was smoking like then when he parked it?  Might tell you if it’s stuck rings or dried out valve seals vs. worn out motor.

@subnet help this feller out

True duals? And does the smoke look and smell like burning oil? I would guess stuck rings on one or more cylinders. It shouldn’t smoke consistently and continuously while idling if it’s valve seals unless the valve covers are full of oil, which would indicate a plugged oil drain in the head.

Plus 1 on the rings or possibly valve stem seals.

My 460 is doing the same thing and I’m gonna have to take it out again.

Do a 460 swap! You won’t miss the FE when you have 500+ lb ft of torque

So, I pulled the plugs.  All were filthy.  2nd and 3rd one back appeared oily.  I then pulled the valve cover.  Zero sludge.  I don't see blockages on either oil hole.  The pedestal is darn clean.  I pulled and inspected it.  It almost looks new, lol.

I'll pull springs tomorrow and inspect/replace the valve stem seals.  

Seriously, thanks for the replies, guys.  I suck at this but yall are making it kinda fun!

ETA-  the second pedestal bolt hole on the head had a "bowl" kind of milled around the threaded hole.  All others were flat.  Is that normal?