I believe it's the np435, but I could be mistaken...I'll have to take a look see and find out. The 300 is one of my favorite motors, but this one needs a little help. Runs great but I'm thinkin it's a headgasket

That's what I thought it might be.  I would love to throw a Ford 300 + t18/np435 in a  Toy.  I've got a 89 Bronco with a 300 EFI on my parent's farm in Kansas.  Probably it's the 435, but it;s still a hella low first.  If I had the resources, I'd do the t-18, toy case, and toy axles and call it good.  I've got all of these, but they are in different parts of the country.

But damn, I love that 4.9!!!!!!!