i would do some 411s and only way it will shak is if like said before not instaled right

 

So the possibility of shaking is there....do any of yal stay in Houston if so anybody know who does Install of 3.73 gears at a good price and quality work....

 

Which heads does yours currently have?

https://www.performancetrucks.net/fo...g-info-434396/

 

The possibility of shaking shouldnt be there at all. If it shakes, or whines for that matter, they arent installed correctly. If they are done to specs, it wont feel any different then how it does now at any speed, concerning vibration. Dont be worried about doing a gear swap. Just make sure who you pay to do it is experienced in it.

 

I bought a pair of 243/799 heads off a 08 5.3

 

Those 243/799 heads are indeed relatively stout performers…straight out of the box.

Merely asking your existing CH setup to volunteer a wild guess at estimated HP gain!



;)

 

i gained 52HP at the wheels from 799 heads milled .030 and NNBS intake with 30# injectors and 92mm TB... Flaco tuned it for me. Truck doesn't die off after 4500 anymore

this was on an lm7 FBO with TR220 cam and 3200 stall

 

Cool I'm just looking for some gaskets and headbolts now and install can begin

 

I do have one question man what's the difference between the stock 799 heads off a 08 5.3 then the stock heads of my 07 5.3?

 

Somewhere between negligible and substantial. Your 2007 5.3 is factory rated at ~315 HP, yes?
Of course GM’s VVT, AFM and flex-fuel variations are thrown into our Gen III/IV mix - often with essentially the same head.

Note the 243/799 casting numbers denote only a generic pre-machining lump from the foundry, and that several seat/valve/spring iterations ultimately evolve from those.
Not trying to be a dick about it, just don’t want to see anyone throwing good money after bad.