Picked up a 71 413 rb engine in parts. Is there any value to it or is it just scrap weight, Guy thought he had a 400, but he was wrong.

I seem to remember something about the 413 vs the other bb truck engines, somehow I think they were torquier than the other's (all else being equal)

I don't think there's much demand for them, BUT...list it and see what happens.

I bought a 72 413, they are industrial blocks much stronger than the car blocks. Thicker cylinder walls. A lot of racers buy these to make into 426 race engines.

Did they actually sonic check the blocks?

https://arengineering.com/tech/sonic-checking-the-mopar-big-block

When mine was bored out to .060 over the guy said it had enough cylinder to go another .060 easily. He also said it was the best sounding bore he’d ever done (big machine shop in Richmond who did a lot of race engines).
Chrysler made these marine-industrial blocks to withstand extreme duty environments like 80 ton cranes (what I got my 426 out of), CT 800 dump trucks. A lot different than motor home blocks. Most everyone running a Max Wedge in Stock or Super Stock look for these blocks to build a strong racing platform.

What's the casting number of those blocks?

There is no casting number just the date, Jan 72. A whole different animal then regular blocks

Front pad

Small (6”) but thick balancer

Look on the back of the block bell area near the sender area for the casting number.

Quote from 440 source.
[[[[[[[[[[[[[[[[[[[[ For most applications, this block was used for their "Heavy duty truck or industrial 413" engine. This is the setup with the huge (5 bolt) water pump and housing and very large cylinder heads. These engines were used in lots of motorhomes, large (semi) type trucks and other industrial applications such as generators, pumps, etc. The water jacket cores (or what could be considered the "outer walls" of the cylinders) from these blocks were essentially those from a 440 engine. 413 bore size is about 140 thousands smaller than a 440, making these blocks essentially an "underbored" 440 from the factory. This results in the cylinder walls usually being over .400" thick on these engines. This means that these blocks can be bored out to a 440 size, and used as a 440. Once this is done, it results in standard thickness cylinder walls of .250" (quarter inch) thick, which is Chrysler's standard specification for cylinder wall thickness.

Although the vast majority of these seem to have been made into 413's we have seen some of these made into 426's from the factory (often in boats for marine applications) and VERY rare examples where Chrysler themselves assembled and stamped these as a regular 440 at Trenton. This may have been due to a shortage of standard 440 blocks, or the need to use up "old" inventory, or some other similar "keep the line running" type of reason.

Unfortunately, the internal main webbing and main cap setup on these is identical to a standard 440, not any thicker. This was a missed opportunity. Imagine if Chrysler would have increased the main webbing thickness on these, similar to how they did on the early "230" casting 400 block, and maybe even gone with the cross bolt main capped Hemi type setup. We would have had "somewhat" plentiful 1000 horsepower capable factory "440" blocks available.

Interestingly, some early examples of these actually do have the "cross bolt" bosses cast into them, indicating that they were thinking of doing this, but never went ahead with it. Or they may have been cast only to use in the super stock programs. But these early examples are extremely rare. It is likely only one or maybe a few early production runs ended up with the cross bolt bosses. We've had hundreds of these blocks (most all out of motorhome applications from the late 60's/Early 70's), and none have ever had the cross bolt bosses. Here is a picture of the cross bolt bosses shown below: ]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]

Yep, where the numbers are