I found a 390 in a 1976 F350; will this engine fit in my 1969 F250? Does anyone know if I will need to do any mod to the distributor?
Thanks

 

Yes it will fit....however what was in the 69 before? If it was an FE engine, like a 360/390, then the swap is a lot easier. If not You will need the engine perches, tranny, carb linkage, exhaust manifolds, maybe the rad, and probably a few other things I cant remember right now.
The distributor is most likely a duraspark. So you will need the ignition module and the wire harness between it and the distributor. Then to hook it up you only have to connect two wires to two different power sources.
Check out this link for details.

https://www.ford-trucks.com/DurasparkII.html