All things being equal (and flat) I wouldn't think the reliability between the two transmissions is an issue. It really boils down to what you are going to use it for. If you have lots of slopes and hills, naturally the transmission is going to work harder. If its going to work harder, a more capable transmission will naturally 'work less' then a less capable one.

The K58 has a charge pump, larger fan, and is Tuff Torq's next gen transmission (having benefited from current R&D and testing). For me, the $600 for the X304 is a no brainer when considering slopes and hills. Thats exactly why I bought one.

Remember, the extra 600 not only buys you the better tranny, you get the AWS and larger rear tires.

My 2 cents, having been down the exact same road.

Jopopsy

PS If you are also going to haul a dump cart up those slopes and hills, I'd definitely get the better tranny. Its made for that.

thanks Jopopsy..... the bigger part of my question (more than which transmission is better.... had that part figured out) is the reliability of the x304 / likelihood of the extra moving parts breaking...

Some will argue that the K46 in the X300 will not last 15-20 years on hills. Their judgment is based on the fact that it's a "small" transmission. Nothing to do with known or predicted reliability. Having said that, observed reliability over that time frame is unavailable (product is too new), so it's a guess. There are some K46's out there that have failed - I'[m sure you'll hear about it, but considering that there are millions of them out there, the small quantity that failed is irrelevant.

But the fact is, if you use a Mack truck to deliver pizza - it will last forever. So although the logic that dictates that a larger transmission will last longer is still valid. Question is: will a small one last 20 years, and a large one 40?....

To be on the safe side, and considering that you want 15-20 years, I'd move up one from the K46 - thus go to the X304... you're buying safety margin. And $600 over 20 years, translates to $30/year... Peanuts.

Maybe U should consider the 320 since U want the better
hydro, an AWS isn't important to U.. Get U bigger deck
and more HP too...
Paul R...

love the idea of the 320, but the 304 already more than i was hoping to spend... and NOTHING used at my local dealers...

so 304 the likely candidate if i can get comfortable about the AWS holding up

JD has been using AWS for quite some time now. As w/ most things on the X series tractors, it's pretty heavy duty back there. Personally, I wasn't overly concerned about the AWS holding up.

JD has run AWS on the lawn tractors since 1998 (LX277) and they have held up fine. The new system is even beefier and steers easier so I'd have no worries. JD has had AWS in garden tractors since 1992, so it's not new to them.

my dealer told me the same thing engine tech said above.

jopopsy. you mentioned the 304 has larger tires. my 304 has lower profile tires to compensate for the 4ws (larger wheels), but has the same size (20") tire as the 300.

ridonkulus,
Yes, but even though they're the same size, the bigger rims offer more "bling."

In all these discussions on transmissions as of late, I hear a lot of talk about hills and pulling, but one thing I haven't heard mentioned is rider weight. I know some guys who weigh less than 160 lbs (and lots of gals). And I know some guys who weigh nearly 300 lbs (and one guy who weighs 400+). When you're talking about longevity among tractors which aren't made to pull, there's a big difference between a tractor hauling a 150 lb guy up a 5% grade and a 250 lb guy on a 20% grade.
If my 400+ lb cousin-in-law ever had a yard big enough to justify a mower, even if it were perfectly flat and he did nothing but cut grass, I couldn't imagine any lawn tractor which would surive a season hauling him around.

Marieguy ... Not sure about the trans holding up with your 400+ lb cousin in law , but I would bet you $5.00 to a dog turd ( you can hold the stakes ) that the seat wouldn't hold up.... LOL

Marineguy,
That's some cousin-in-law! If anything that heavy is in my yard I want it to be eating grass, not mowing it. Off topic did you see where the Germans have been doing studies on migratory birds and they have found that the birds have specialized cells in their eyes that can "see" the magnetic lines of force of the Earth's magnetic field? Gives them the first version of a HUD for navigation. 'Course that just gets me thinking that someone in the Pentagon will want to cross a goose with a SEAL...
I was going to ask you, how much extra ability and/or survivability does the Osprey give over the Jolly Greens? I'm always concerned about our reliance on high-tech and of course the Russians have some pretty amazing planes that fly without massive computer assistance. Also they are designed to operate out of some pretty crappy airfields. Add in the fact that the Chinese seem to be trying very hard to find ways of fouling up our technology... I know that American aviation has done well when it comes against Russian planes but I suspect that is as much to do with the quality of pilots as anything else. I'm sure its somewhat different but we had some Ukrainian docs over for an exchange/learning program. Let's just say if I'm ever in the Ukraine I don't want to get sick.