i have a 71 f250 that had a 390 in it .a friend of mine has a 6.9 and a 7.3 .how much work to put either one in my 71 f250 .with the price of gas lately.is it worth the work.the 71 f250 has a t18 trans with a dana 60 with 3.73s traclok posi.i have a 300/6 also but a diesel should get better mpg
thank you
lrd56 a happy dinosaur

 

It is gonna take some serious work, but it can be done.
Gas and diesel trannies are not interchangeable with each other.
You are going to need a bigger radiator.
You will need to install two batteries.
You also need to install fuel return lines.

The electrics of the engine will not be to hard.
The weight will be a little more than a gasser.
I do hope it is a heavy duty frame as well, some of the 250 light duty frames would be a little thin.