Waiting on some 4.30 gears

[sloCaddy]

its an 03- i'm not sure if its 4l60 or 4l65? anybody know how to tell diff? glove box code or on tranny? I just have one tire fire, no g-bomb here, and barely enough power to fry one tire let alone two.

[Green Machine]

its an 03- i'm not sure if its 4l60 or 4l65? anybody know how to tell diff? glove box code or on tranny? I just have one tire fire, no g-bomb here, and barely enough power to fry one tire let alone two.

Really no differene in trannys they r both weak. Do a 4 80 swap and don't look back. If u want to keep ur 4/60 do circle d 278mm stall if u tow. It will wake up that 5.3

[TXsilverado]

you never know with driveshafts. i've seen stock ones break at 100mph with 3.42's and some live up to 140mph with 4.10's.
GM's driveshafts aren't meant to spin as fast as we make'm, hence speed limiter. Yes there are many out there going past the shafts critical speed, but you never know until you try it.

i must be one of the lucky ones. i take mine to 130 all the time on 4.30's. the 2 piece driveshafts seem to be stronger from what ive seen though.

[TXsilverado]

i think you would be around 2520rpm at 70mph with 28" tire 4.30 gears and about 2410rpm with 410s.

converter locked with 4.30 gear and 305/45-18 tire puts me between 2400-2450 RPM. 7100 rpm puts me at 132 unlocked if anyone cares lol. i know my max mph unlocked was a question i couldnt get answered when i was trying to decide between 4.30 and 4.56.

[farmtruc]

i must be one of the lucky ones. i take mine to 130 all the time on 4.30's. the 2 piece driveshafts seem to be stronger from what ive seen though.

oh ya, not really lucky, now you're talking two shorter shafts, which just increased the critical speed considerably.
for the long trucks out there, 2 piece is definitely the way to go for high speed.

[slowxcab33]

That answers my question. Thank you Allen.

[sierraman05]

Really no differene in trannys they r both weak. Do a 4 80 swap and don't look back. If u want to keep ur 4/60 do circle d 278mm stall if u tow. It will wake up that 5.3

hate to thread jack but i have 05 gmc sierra cc z71 3.42's looking to tune it soon, what would the benifits of getting the circle d 278mm be or not much for me with those gears