I am used to the rod section of the crank to have a hole bored in it. I have had this for decades but aside from being forged I know nothing about this crank.

Could it be a 273 or is it a forged 318/340 crank and I am only used to seeing cast ones?

Measure the bearing journals.

I'm probably wrong but I think the forged 318 cranks had solid journals like that and the forged 340 cranks were drilled. Not sure on the 273. If it is of small block crank dimensions. 360 cranks were cast and had bigger mains and a longer throw than the other LA small blocks.

I will measure the journals tomorrow.

I know for a fact is isn't a 360 crank but didn't think to measure it.

I always thought it was a forged 318 truck crank but never got around to looking too deep at it.

It's definitely a forged crank (from the wide mark on the rod throw).

You can also tap it with a hammer - I've read that the forged cranks will ring and the cast ones just thud... I don't know if this actually works, I've never had a cast crank

That is a 273 or 318 forged crank. I’ve got several of them.

Only the 340 crank had the hole in the journal. Looks like a forged 318 or 273 crank.

I've got a spare 340 block.

Any sense making it into a 340 motor with this crank, or will it be too far out of balance to make the balancing financially reasonable compared to a new crank?

318-3 truck crank. Back in the day those were some of the best cranks for small blocks. Still good but heavy!

you have a PM on this

273 and 318 used this forged crank as long as they came with a forged crank, 69 273 automatics were cast as were 69+ automatic 318s for a while then even manuals got cast cranks, I am not sure what year the manual 318 went cast. The only significant difference in this and 340 crank is the drilled journal, the 340 had a heavier rod and piston requiring some weight removed somewhere to balance it so a hole drilled in the journal it was. You could run a really light rod/piston to get close enough to balance it normally or better yet, drill the hole AND run light rods pistons AND balance it properly to make it real light and strong.

I’ve run that crank in a 340. You just have to balance it.