I checked out an ad for a 440 forged crank and came across a deal on someone's engine project so I bought it. Thing is it's a 78 block and I'm curious about how stout these blocks are? According to the 440 source article it has the thickest main webs of all the 440's,I measured.

wouldn't hurt to do a pressure & sonic check (both). From what I read, the later blocks being thinwall ain't true. there is info in the archives here.

I've had a '74, '77 & '78, IIRC.
I don't recall anything different in webs, nor can I imagine an upgrade in strength being necessary with power output so much weaker than say '69-'70.
That said, I don't know if there was a motorhome-oriented block, someone with more knowledge should be able to answer that.
What I DID notice was core shift, some of it rather concerning & not good for big overbores.
Had to sleeve a couple holes on one block due to corrosion not cleaning up.
(Reference: I like .200 minimum on the thrust walls.)
Another thing is the chamfers at the tops of the bores were inconsistent among those blocks, one was pretty wide/deep.

There are no "general rules" for 440 blocks. Each one is a special case. You have to sonic check, magnaflux, inspect, etc. each and every block regardless of casting number or year or what is stamped on the ID tag. These aren't Chevy blocks where some castings were HP with four bolt mains or Ford blocks where some casting were solid lifter or hyd lifter or side oiler or something like that. Mopar RB castings are basically all the same except that the production tolerances were very loose. Each one has to be inspected closely if you're planning on making more than 600 hp.

The later blocks have a thicker webbing on the side that earlier blocks don't have. Also larger water jacket ports to the heads.

That is somewhat irrelevant as the holes in the head gasket manage flow thru those ports.

Thanks to all that replied. Here is the 440 source article I was referring to.http://www.440source.com/blockinfo.htm

From 440 Source: Shown above is a picture of a 4006630-440 (1978 model) 440 block. The "A" measurement typically is about 3.190". This is about 60% thicker than the early 440 blocks shown above. "B" typically measures about .520", which is still about 40% thicker. The blocks with these thicker supports were not cast during any specific date period. There is no external markings or numbers which show they are different from the other blocks. They DO seem to be more commonly used for truck motors, however just because you have a truck 440 does not mean it will automatically have the thicker main supports. One important fact is that while 4006630-440 casting # blocks are the only blocks we have found to have these thicker supports, not all these blocks will have them. There appears to be no other way to tell if a block has them or not other then actually looking at the supports themselves. Without the crank and rods removed from the block, it is very hard to tell.

Either Mopar Muscle or Mopar Action magazine did a test to learn get to the bottom of the rumors. They found that the later blocks were heavier but that the metal was slightly softer than the early blocks. The Warnings that Larry Shephard and other Mopar Performance reps told about late blocks being "Thin Wall" was wrong.
It makes me wonder whether these guys were idiots or too lazy to check for themselves before spreading false rumors.
I've run later blocks simply due to them being easier to find.

I wrote that article for Mopar Action.

And the link here at Moparts for that article now goes to a brake upgrade article.

"Sonic Checking the Mopar Big Block goes to --- brake-upgrade

Later blocks probably have less nickel and tin than the earlier one. That also holds true for Chevy and Ford.

Here is a 76 block that I'm building right now. Earlier blocks don't have this beefy rib on the sides

Here is a 75 block that is my car. Has a rib but nearly as big as the 76 block.

Also both are 630 blocks

True but the 76-8 452 heads also have larger ports so increased flow to the heads may have been a goal.

IIRC, the enlarged water ports was to ease removal of the casting sand.

That was a great one too. Thank you for the research!
I notice that you don't toot your own horn although you have accomplished many things.

That doesn't surprise me. A few years back a whole bunch of the links got broken and moved around during one of the upgrades. Most of the older articles were lost. Guess they disappeared into the internet black hole.