1968 Dart question....

Guys,
I got a real crazy question. First off a bit of info on the starting of....

As a few know, my Dad passed away alittle over 2 weeks ago.....Well to my digging around his shop (Small engine repair) I found some paper work on a 1968 Dodge Dart he owned, and traded off.

Upon finding this paper work, I found the guy he traded it too, and for what he got for it.. (as crazy as this is, I could **** cinder blocks *OUCH*) He traded this car, he had, that was a turn key, jump in fire her up and down the road you go. car, for. getthis a damned farm tractor! A old 1942 Farmall "H"..........turns out, this tractor sits buried in a garage of my Dads (or well was my Dads, that he rented!) and hasn't run since the trade!

The owner of the now Dart car has been contacted and spoken too by me and my Step-Mom as this tractor and car was traded back just before snow fell this past winter. With the paperwork I found the owner of the tractor (now the Dart was to be a RUNNING Farmall "H". It was noted as a "Hauled in trade" with pictures there of it coming to the garage it was found sitting in, buried.

The question is, The Dart. It was a turn key EVERY DAY runner, but, it had whats said a 318.....LA type motor. IS this a factory install or was the Dart not offered with such?

I ask as my Step-Mom and I have been talking about this odd trade that well she told me he (my Dad) should have been slapped for such a trade but...... that was my Dad, and I know and she does too, that's just how he was......

I'm trying to see about making this trade right, or giving back the POS Farmall, to get the Dart back......(I'd take it as a "project car") and to see what it might need as from what I have read this car was in good shape and was inspected last of 2012!!!!!!

One picture actually does exist, its a 4 door model, and is dark green FACTORY paint, and all the Chrome intact, and looks to be a pretty clean car otherwise, except for the interior, no shots of what that may look like exist.

Any help on what the motor could have been in this car if not the 318? And if not, what all motors were offered factory? I'm not 100% knowledgeable on this one.....

Thanks guys!