Can I put a transmission from a 99xk8 (zf5hp24-26) into a 98 xj8 (zf5hp24-15) without any problems. What is the difference between the two models.

I have done swaps like that and had no problems. I've read about people getting faults indicated after mixing AJ26 and AJ27 gearboxes.

If there are differences enough to flag faults, they are with the valve body and not the mechanical gearbox itself.

Lately I just keep a good used gearbox with new forward drums for each application (AJ26 and AJ27).

I would replace the 'A'drum in the replacement because it is easier to do it now rather than later.

bob

Thanks for the reply Bob. I do plan to put the updated A drum in the transmission before installing. If the only problem, if any, would be in the valve body it can be changed after the transmission has been reinstalled. Is there any difference in touque converters?

I'm curious where did you get the -26 and -15 for the ZF5HP24 designations from? Please enlighten me. Thanks!

They are the last two numbers of the model number on the green plate on left side of the transmission. 15 is from my 98 transmission and the 26 is from the 99.

It just dawned on me that you can call ZF technical support based in Chicago to find out if they know what's the difference between the two versions of 5HP-24's you have. They have been very helpful to help me trace my tranny to the A-drum's failure.

Finished installing the transmission today. The only issue I had was that while I was about to install it I noticed that the end of the transmission, I know the part has a name but I don't know what it is, where the mount attaches was broken off. I took the one off the transmission that came out of the car.
I took the car out for a test drive. It shifts smoothly in regular or sports mode. The only problem is on the first run it died when I came to a stop. After diving it a little more it didn't die but I can feel it labor as I stop.
I did a little research and I believe it is the torque converter locking up. I'm going to drop the pan and replace the lock up solenoid with one from the transmission I took out of the car.
If anyone smarter than me, which is about 90% of the members, has any ideas it will be appreciated.

You're way ahead of me on the transmission as I don't know which solenoid does what. But the dying when stopping can also be a dirty throttle body/sticking butterfly.

I found this discussion on the Range Rover forum that shows which solenoid it is.
https://www.google.com/url?sa=t&sour...XNhv_a9DmtvNNQ

I don't think it is yhe throttle body because it feels like its in the transmission. The solenoid is an fairly easy fix so it's worth a try. Thanks RJ.

Today I dropped the pan to replace the clutch lockup solenoid. With the pan off I compared the valve bodies or the 99 and 98 transmissions. In the attached photos I noticed the some of the solenoids were different colors. The one with the blue solenoids is the 98( model 15 ) and the other is the 99( model 26 ). After seeing this, and Motorcarman's saying the the only difference might be in the valve body, I decided to change the entire valve body. While I was at it I insalled the Transgo pressure regulator. Got it back together then took it for a drive and it doesn't stall at a stop and shifts beautifuly.
Now I have to fix other bugs.
ABS- traction control faults
Replace sunroof
PECUS R
Since xk8 transmission in now in a xj8 I will posting these issues on the X308 forum. Thanks Bob and RJ for your inputs.