Help on RE Assembly Specs

I have no idea what the specs are on my 04 Tundra rear end assembly. I need to find and replace the rear axle and differential. I have a mechanic that will do this for a very good rate if I bring the parts. 4dr SR5 with a 4.7L V8 and 6 lug wheels. My original window sticker shows model # as “7744A”. It is a 4 speed 2WD. I understand that gear ratio is important but I’ve also heard you can go from a 300 range gear to a 200 range gear to help get better gas mileage. I could really use help from y’all so I don’t buy a new one from the dealership for $3k-$5k. *Edit* I was told by the mechanic that the entire rear end assembly should be replaced. He tried explaining why this route and not just the differential but I don’t understand it. I’m not doubting it right now since he’s not charging me much for the labor and isn’t working me over on parts. I’m confused.

 

The rear end in your Tundra is likely the 4.10 gear ratio now. A suitable donor would be any Tundra with this rear end. These trucks also came with 3.91 rear axles in many of the configurations. Either will work in a pinch if you just need to get on the road. The 4.10 will get you off the line a little better and is what likely came with your truck. I would stick with that. The "300 to 200" business has nothing to do with your Tundra, ignore that. We're working in the "300-400" range so to speak. anything below the 3.91 would be regrettable. I'm guessing the rear end needs to be replaced due to rust?

 

thanks for the reply and info! No not rust. There were metal shavings and small pieces in the gear oil. It was drained to diagnose the road noise I was hearing.

 

If the housing is ok and not rusted, you'll only need a complete 3rd member. That is the part that unbolts from the center once the axles/driveshaft are removed.

Complete 3rd would include the gears, bearings and either an open or LSD (depending on what you can find). These would be all the parts that could have failed.


Where are you located?

 

I’d take it to a rear end shop and just have the 3rd rebuilt.

 

I am in west Texas, the Midland/Odessa area. I’m confused as to why the mechanic said the entire rear end needs to be replaced then. He’s not profiting from this besides the labor (and he isn’t charging me much at all). There is no rusting at all. Thank you for replying to this.

 

Are you lifted or running larger tires? LSD or non-lsd rear end?

Now would be the time to change them.


I may have a complete 3rd for sale in a couple weeks. Choice of 4.88 or 4.10 and an OEM LSD. I may rebuild the LSD too.

 

No lift. Running this 2wd 265/70R16’s. Yes, this is a 4.10 w/ LSD. I am putting it on the 04 Tundra my son will take this summer as he heads off to college. Want to make sure all is road worthy, especially since he’ll be over 500 miles from home.

Still not sure why I was told the entire rear end needed to be replaced as opposed to just the 3rd.

Thanks for the reply. Keep me posted. I am interested for certain.

 

Maybe he would prefer the entire axle assembly for ease of installation. Unless the axle housing is rusted, which can happen, or bent, you should be ok. More explanation from the guy could help.

 

Good points. Although this is an 04, it’s been well maintained in this dry and hot climate. There is no rust and, as the sole owner, there have been no accidents or incidents to bend/damage the axle.

While I have no issues working under the hood, I’m not experienced with this type of repair so I’m not sure on ease of installation. I have read several thread comments that it’s actually easier to replace the 3rd as opposed to the entire assembly. Either way, he quoted me $550 labor to replace the entire assembly. I can either provide the parts or he will find them and have me purchase and send them to his shop. I’m beginning to think the labor may be high.

 

I’ve never done the third member on these trucks, but I have another vehicles as well as an entire axle assembly. Don’t forget, there will be the breaks to contend with and all their components. From the outside, I would think a third member would be better suited for your circumstance.

I think at this point, your best bet is to take it to and axle shop that can give you a proper diagnosis and estimate with parts included. You might end up cheaper than trying to source for this guy. Hopefully you have no leaky seals on the axle shafts and it can just be a slam dunk rebuild.

 

Swap out all the everything. Measure across spring pads (or weld em), go to a junkyard and find something with rear discs and 3.55s and 6 lugs. If you’re cool, lsd. If he’s not, open.

 

Will do.

Possibly but that doesn't make much sense to me. The 3rd member on these is easy to pull if no rusty hardware.

Yeah, 3rd is fairly easy to pull. Put rear on stands, remove wheels, drain fluid. Disconnect park brake line (unclips), undo 4 axle/brake assy retaining nuts, loosen brake line and slide axle/brakes out as an assembly. Undo driveshaft and 10 bolts to pull 3rd member out.

 

Thank you very much. Great information.