madmann26

iTrader: (7)

Yes, it's a 10-bolt. The 8.5/8.6 designation gets used interchangeably but for all intent and purposes it's an 8.6.

Don't do a 3.23 - 3.55 swap. It's barely a difference. The 3.73 swap is viable, depending on the goals for the truck. I personally, would do the 4.xx swap.

EmmerichLSx

iTrader: (5)

I have a set of factory GM 3.73's I'll let go for a good price PM me if interested.

Northeastconfederate

PM sent.


I'm very reluctant to go with 4.xxx gears on the street. Especially considering it's a DD. 3.73's seem like a good choice, though.

So maybe first moves ought to be gears and maybe a converter, say 24-2600. Headers, cai after that, and maybe a mild cam.

03sierraslt

iTrader: (22)

I didn't read the whole thread but what size tires and what trans?

mvrk10256

I built the trans and felt a small stock upgrade was in order. I think it cost me like $80 from transgo. I made no programming changes, however the valvebody on the trans was modified.

Bluecollar Hotrods

iTrader: (18)

34" tall tires? ****, that thing must be a slug with 3.23s. I absolutely would not do any less than a 4.10 gear. Personally, I'd go with 4.56s if it were my truck. I have 4.11s in my own truck with a 4L80E and 31" tall tires. It's a great combination, my friend's 04' 2500 HD has pretty much the same stuff from the factory - 4.10s, 80E, and 31" tall tires.

You have a 4000+ lb truck with an engine that likes to rev, don't fear the gear!

94_C/1500

With tires that tall 4.56 isn't out of the question. It's not uncommon to see 3.73s stock with 265/75R16s stock.

Northeastconfederate

I hear y'all about the tires. But I won't be keeping 34" tires on it. It's a 2wd truck, 315 70 17's on the back, 265 70 17's on the front. Looks cool as hell, like a dragster. But with that much differential f to r, the traction control, abs, etc are all freaked out. Had to pull the fuse for power supply to those. So I'll be going to something with a shorter profile that's close in height to the 265's.

Yes, it's a slug with 3.23's and 34 " tires!

Vortec350ss

iTrader: (20)

The Sierra Denali I drive came stock with 4.10 gears and the factory size tire is a 265/70/17. Youre crazy if you re gear for performance and go with less gear than that. Remember thats GM's luxury truck and they chose those gears... There are basically no negative side effects. Highway mileage would only suffer if you cruise at 80+... and even then I'm not so sure. The load on the engine is so much less with more gear that it has to do less work.

Dan Neumann

I just put a CVC made Trailblazer converter in my truck yesterday. I was given it for free from a guy who put a 4L80E in his truck and he only had about 500 miles on the converter. Motor is a 4.8 with a Comp XR265HR-14 cam. Gear ratio is 3.73 and stock height tires. So far I'm happy with it.