im about to start a build just trying to price some things out and i have a used 4l60e that i have laying around. How much would a full rebuild on it cost to handle around 600hp on the daily, i dont want to spend a crazy amount and break my bank and my feelings. or recommend me another trans for my buck, thanks in advance for the input.

 

This recent thread should give you some ideas:
https://ls1tech.com/forums/automatic...arts-list.html

You might also look at the parts list for the FinishLine Transmission Level 5:
http://www.finishlinetrans.com/trans...vyDuty4L65.htm

For 600HP, I would add the Sonnax Input drum, billet pump rotor and a billet output shaft. Those are all included in their Level 6:
http://www.finishlinetrans.com/trans...meDuty4L65.htm

At 600HP it may be cheaper (and more reliable!) to install a 4L80E.

 

does finishline sell it as a kit, i have someone to rebuild it for me already

 

No FLT does not sell it as a kit; the intention was to give you a list from a reputable source, instead of just from me.
Many parts are on Amazon.
I keep trying to get TruTechTrans to come on as a sponsor as they sell both kits and build transmissions. They may not have the billet output shaft and pump rotor; I think FLT will sell you those parts.

 

For years I have used the "stock" input drum almost without problems. If flexing were so bad, GM would not be able to get 250,000 - 300,000+ miles out of these transmissions, and I would not be able to get many hundreds of passes (in 9 & 10 second vehicles) out of these units with very little "if any" problems in the 3-4 clutch area. Very rare does the snap ring area break. I have been called a "minimalist" by Frank as CPT. For 38+ years, I have learned to work with what you have and solve problems without throwing a lot of money at it. Sonnax solves problems that in the vast majority of cases exist at a minimum and they charge a lot of money for the fix.

 

Dana, you like Dynamic396, Clinebarger and other pro builder have the experience to examine a used input drum, listen to how it rings, etc, to determine if it can be reused.
Us DIYers don't have that experience. Nothing that a DIYer hates more than to rebuild the trans, install it and have a previously marginal part fail. Hence, I encourage DIYers to "throw a little money at it" and upgrade more parts than are probably necessary. Partly to ensure that possibly-marginal parts are replaced.
So sure, DIYers that are following my advise over the past few years are spending a bit more money than they need, but seem to be very happy with the results. And the success rate seems to be higher than before.