Transmission Conversion

Has anyone successfully removed the 'junk' ZF Meritor 12 speed transmission and replaced with an Eaton Fuller 18 (or 13) speed transmission? I have a 2005 Freightliner Coronado with a 14 liter Detroit. I would like to know what company or website to check with. My truck is great, not so much on the transmission. Thank you for any help!

 

The problem with the ZF is that it shifts poorly, if there is an emergency I cannot get the tranny to move quickly enough, and I just do not enjoy driving this vehicle because of the automatic tranny. I am very interested in keeping this truck, I have generally had 18 speed transmissions and if there was a way to switch out the transmission I would be very interested in knowing where I could get this job done. I do have a manual and I feel as though, yes this could be running perfectly, but I do not want an automatic tranny. Thank you for your feedback.

 

The clutch fork was replaced 3 weeks ago, and because this is a ZF Meritor, which no longer exists, the 'new' clutch kit Meritor sells for this transmission has not only plastic bushings, the entire tranny must be removed to replace the part. I went to a machine shop that does specialty parts and had bushings made and had the part basically remade, this cost me $2000.00, that is with the cost of the whole replacement job. The price was a little less than 1/2 of the cost of having the crappy plastic kit put into my rig. I really want to take this transmission out and replace it with a manual. Does anyone have an idea if the automatic transmission could be replaced with a manual one? I do not want to spend thousands that I don't have to because Meritor will not stock the less expensive parts. Also, I know how to work on a manual tranny myself and I prefer knowing if the fix that my mechanic is suggesting is necessary. There is a BIG difference between the $4500.00 that I was told a clutch would cost and the $2000.00 that the fix cost because I knew enough to look in the manual myself. Oh, and because that part is plastic the part would wear out in approximately 2-4 years, so this is gonna cost me in the future, if I grease properly the clutch fork I just put in would last another million miles, that is how long the original clutch lasted. Again, I would like to know who can change out the tranny, I would like to have a manual tranny. Thanks!