My 98 Diamante has a transmission oil leak on the passenger side drive axle. There's some movement from the shaft as if the bearing is worn. The driver's side does not have this movement. Would it be advisable to change just the seal or would changing the axle correct the sloppy fit and movement? Or does the transmission have to be disassembled?

Not sure about this model but the first generation Magnas have a c-clip on the end of the driveshafts which go into the transmission. If that breaks or becomes distorted, there'll be movement on that driveshaft and consequent loss of oil.

a tiny bit of movement is normal.

A seal replacement should stop the leak

You mentioned that the axle moves - I take that as meaning that it slides out of the gearbox housing more than on the driver's side. The c-clip is designed to prevent it over travelling in that way. I'd say if you have a groove cut into the driveshaft, it's a fair bet that a c-clip would need to be on there. Obviously you'd have to remove the driveshaft from the housing to determine that, if you can't get a picture in the manual or somewhere. It's probably easier to look at a new driveshaft at a car parts store.

The most important thing to remember though is that the C-Clips aren't interchangeable. If you can't get one for your model driveshaft, don't use just any one. But for a 1998 model, it should be a part available from a dealer. It's inadvisable to use a used one because they can distort a bit over time, and often don't perform as well after that.

Okay, an update.

I replaced the tranny with a cheap rebuild... but I still have some problems. The tranny shifts great when at a standstill, and it works just fine in reverse, but when you begin in drive, it starts moving great and then suddenly feels like you're in neutral after you get to about 5mph... nothing looks/sounds weird or anything. I tried all of the drive gears OD through Low, and it keeps occurring. Then I put it in reverse and it works just fine. I switched the two gear sensors from the old tranny to the new one (since I knew they were good) and it's still not working right.

Do you guys have any suggestions?

sounds like the torque converter/or oil pressure is low

is the fluid level between the two marks ?

have the place that fitted the autobox do a torque converter stall test for you

you have the wrong transmission installed.

you have a trans for early 97s installed. They do not have a one-way sprag clutch on the low/reverse brake. The TCM is unhooking the clutch pack as its suppost to on the later trannies at speeds over 5 MPH..

basically, there was a change from early 97s to later diamantes. you need to replace the trans with the correct one.

Oh man - I hope you're wrong for that guy's sake.

im not.

You were correct. I ended up going back to the yard where I got it for $450, and they conceded they were wrong when they sold it to me. I got another one valued at $1,200 and they ate the difference in cost. (IMG:style_emoticons/default/smile.gif) Problem solved.

You already installed it? You work quick. It took me all day to put in mystupid alternator - lol

Well I had done it the first time in 7 hours. The second time it was about 6.5 since I already knew how I wanted to do it after the first time. (IMG:style_emoticons/default/smile.gif)