Look carefully in any Dodge truck factory parts catalogue from 1961 thru 1968 and you'll quickly figure out that the 251 is a flathead-6, not a slant. It was used in the Power Wagon in those years, having replaced the pre-1961 230 flathead. The 251 flathead was also offered by Chrysler Industrial thru at least 1968 for new installations (you can check a Chrysler Industrial parts and service manual if you like, too), and long after that for service replacement. There is no 251 slant-6. There is also no 240 slant-6, despite mention of a "special 240CID truck slant-6" in amongst other errors of fact in literature published over the years, some of it from sources which should've been reliably authoritative. And there's also no "special 252 truck slant-6" (that one comes from transposing the 2nd and 3rd digit in "225"). As for the guy who thinks he remembers finding a special truck 251 slant-6...I'm sure that's exactly what he said. We can group him together with the guys who come up to you in the parking lot and start reminiscing about their '63 Barracuda with the 383 Hemi. The human memory is not a video recorder — not even close.
Misunderstand or partially-understand something, then repeat it once or twice, then a few people who hear/read it will repeat it once or twice each; repeated often enough it becomes "common knowledge", true or not. That's how it works at the chit-chat level of forums like this, and it's also how it works at the publishing level: Someone is tasked with putting together an article (book, manual, whatever) about the slant-6, they have a deadline, they don't quite check their facts carefully, the book/magazine/manual gets printed, and suddenly "it must be true, I read it in a book!.
I intend no offence or jab at you, GhostDuster, but please have the grace to say "Oh, oops, flathead, gotchya" and let it end.
