First, I have read that the front engine cover on a 4.0 is the same as a 4.6. Anyone know if this is fact? If so, why is it that all the front engine covers for the 4.6's are sold out and the ones that are left claim they won't fit the 4.6?

Secondly, is changing the front engine cover and oil pump a potential remedy for imploding/exploding oil pumps on '03's? The logic seems sound; if the first one lasted 100K, the second should last about as long (always supposing you do it before the block self destructs).

 

I've heard they're swappable, with only subtle differences like location of the oil sending unit. But I don't know the accuracy of that. I'm in the same boat and am planning to just swap gears and reuse the cover. My engine is an '04 if that makes any difference when it comes to reusing the cover from an '03 vs. '04.

 

L.R.Series (http://www.lrseries.com/) sells the front for 390 pounds (~$500). My concern with reusing the front is that if it is already suffering from metal fatigue, it may fail anyway....

 

First, before I forget, why are you wanting to replace the rear drive shaft, there is nothing wrong with the factory rear with a roto-flex, save your money for something that will improve your truck.
As for the front cover, go to, http://www.bputah.com/ click on D2 parts then front cover and read up. Why are you wanting to replace your front cover, is your engine on the list, are you having low oil pressure issues? If no current issues, then first check your oil pressure when cold at idle and at 2000 RPM's then at operating temp at idle and 2000 RPM's, let us know what your pressures are.

 

Mike, I was under the impression that the roto-flex disc was the weak link in the rear prop and that they need to be replaced periodically because they get shredded on trails. I know you're sold on these from other threads, but my first impression was, "Why the hell is there a freaking hockey puck in the middle of my prop shaft?" Why do you prefer the disc over the two u-joint rear shaft?