There were a variety of forums to put this post, but I think this is the most appropriate.

I'm moments away from a final decision on my engine swap. However, I only want to swap the engine - leaving the stock 4sp and rear in place. Both are in top condition. I currently have the stock L-48 running in her now.

Here are the stats on what I'm looking at:

HORSEPOWER AND TORQUE CALCULATED AT FLYWHEEL.
BORE 4.030" STROKE 3.75
PEAK HORSEPOWER 447 @ 5500
PEAK TORQUE 454 @ 4500
COMPRESION 9.5:1

Will the stock trans/rear hold up ok with this engine?

initially they will but in the long run they wont last. I belive the m-20 coded 4 speeds could handle about 325-350 ft lbs of torque and the m21 coded could handle 375. And then you have the M-22 rock crushes that could handle what ever. If I where you i would beef up the rear and the tranny.

Do you really need that much hp, maybe you could save yourself alot of money if you went with a little less. Maybe the ZZ4, 355hp, 400 torque. GM Crate.

vmikalinis said: Do you really need that much hp, maybe you could save yourself alot of money if you went with a little less. Maybe the ZZ4, 355hp, 400 torque. GM Crate.

Of course I don't NEED that many ponies but the price I got is good and provided it didn't require changing tranny and rear, then why not?

That said, my suspicions are getting confirmed that chances are I'd be better off beefing up the driveline components which I really don't want to do. So I may in fact go down a notch and get the 350/400....