For those that just really want to run an aftermarket diff cover. This is one video, there are a couple more although I haven't seen part 3.

 

Can't see spending the money on one, except maybe for extra fluid capacity. Ford did go to an aluminum finned cover in 2008 for the 10.5, and they call for full synthetic 75w140 in the 10.5.

 

He has a 3 part series also (part 3 not out yet)

 

 

My '06 came with a Hytec cover the previous owner had installed. 6 quarts of diff fluid. Ive had no issues with it for the past 150K miles.

 

Thanks Mark. I meant to post video 2 of the 3 part after I posted the other. I thought it was really interesting. I'm REALLY curious to see what data they have on this.

High HP, from what Gale says, the extra capacity can rob the ring and pinion of horsepower being transferred to the ground through viscous losses.

 

I wonder how much HP would be gained by draining down the over 12 quarts currently in my Dana 135 rear axle?

 

As long as it's at the factory fill level then supposedly it's transferring the maximum rear wheel horsepower available. It's only when using an aftermarket cover that increases capacity that it causes viscous losses.

 

I'm on the edge of my seat! It's more like a season ending cliff hanger! It took two videos to get everything explained, it is going to take quite a few more videos to give us the real world data.

 

 

Yes we do...it's because mere-mortals can't seem to understand the cliff notes version...

 

I'm ok with losing 2hp. These trucks aren't 'fast'...I have a 6 speed go kart that will run circles around my truck and it only has ~36hp. These trucks were designed to pull fast things...not be fast themselves.

 

I do need to replace a cover on the rear and am sort of on the fence.
I think I know what videos I am watching tonight.

 

I have an 08 aluminum (finned) cover that I could let go .............

 

Well the one on it now is very well rusted.
I would be interested to talk about it.