6.9 -- late S/N vs. early S/N block question

[Mad Maxine]

Hi folks--

So, I'm on the hunt for a good rebuildable 6.9 engine, and have been looking exclusively for a late S/N block which I've read is a stronger, beefier block. However, I'm finding that 6.9 engines aren't exactly falling out of the trees.

As I understand it, the later blocks have a heavier webbing up front and a thicker casting around the block heater, is that correct? Are there any other aspects to consider, and are the earlier engines considerably more prone to cracking or failure?

Thanks--as always!
Craig

 

[Kevin 007]

I run several early ones. I just don't use the block heater and use an alternative instead such as a lower rad hose heater or whatever. You probably don't even need one in Texas. I think the early ones lacked piston cooler jets also. But regardless, I have put many many trouble free miles on the early blocks without grief.

 

[Macrobb]

"not exactly falling out of trees" <_<
Too bad I'm on the other side of the US(up north next to Canada), but ovee here they sure are.
I've got three 6.9s sitting under cover that I picked up for under $200, and at least 4 more available in wrecking yards within an hour of me.

Finding 7.3s on the other hand is harder.

That being said... I wouldn't discount a 7.3 if you had one - cavitation is a thing, but proper coolant(Zerex HD ELC is my go-to) will take care of that.
And the 7.3s have bigger head bolts, which is the weak link once you start adding power.

 

[Thewespaul]

Here's a couple local to us, 6.9s are getting harder to find around here, might be cheaper to start with a 7.3 and sleeve it down to a 6.9.
https://corpuschristi.craigslist.org/cto/6127924026.html
https://houston.craigslist.org/cto/6145332204.html