Is the stock transfer case and front diff strong enough for a V8?

That kind of HP shouldn't hurt a 4.3 Transfer case or the front differential. 400 lbft is getting up there. My LQ4 2500HD and LQ9 Escalade engines don't produce that much. You'll likely be alright as long as you don't drive it like you stole it.
Both the front diff and TC are cheap used. Keep an extra set on hand if you plan to abuse your truck. Neither is terribly difficult to replace. There were a few cast iron front differentials installed in S10's, but they're rare. I think they only went into some of the 4.3L - 5 speed 4x4 trucks. My automatic ZR2 does not have one.

So the 4.3 transfer case and front diff are different from the 2.8 ones from 1985? Its an 85 2.8 5 speed 4x4. What would all need to be changed to use a v8 instead?

You will smoke your trans long before you ever hurt the transfer case or front diff.

Unless you're rock crawling or doing major off roading with big tires. That's what kills the diffs.

S10Gary said:

The 4.3 only made like 160hp, would a 250hp or 300hp / 400 lbft torque be too much for the stock transfer case and front diff?

Click to expand...

Just don't Impact Load it.

KJF95S-10 said:

You will smoke your trans long before you ever hurt the transfer case or front diff.

Unless you're rock crawling or doing major off roading with big tires. That's what kills the diffs.

Click to expand...

That, and having a spinning tire suddenly hook, that's what takes out most of the front diffs in GMT-400's.

Salty Crusty said:

That, and having a spinning tire suddenly hook, that's what takes out most of the front diffs in GMT-400's.

Click to expand...

Commonly called 'Impact loading.' Tis the mother of high torque application inventions that cost 10X more than OE equivalent. Like axels , input/output shafts, gear sets, etc

Gotcha. ^ they have some really good CV type axles available, just not really worth it with small ring gear and case applications. I read some testing that was done with the aluminum case'd unit from GMT-400 1-tons. 9.5" ring gear and supposedly underwent upgrades in '97. Iron case available after about 2001, seriously strong. At any rate, they gave it hell and a defective case did 'em in where the ring gear wore against it. I think those axles were about $2500/pair - not for the poor boys.
I think an IFS front like ours that could be swapped out with these units under a RCSB or 2-door Blazer would be almost unbreakable with even a mild LS.