I had an 88 shelby z t top turbo ll car back when they were new. Never had any problems with it for the 87,000 miles i put on it. I did the usual maintenance items. Tires, brakes, oil changes, tuneups. One clutch at 50,000 miles. And 1 O2 sensor under warranty. Was a very good car.
The shelby Z A-555 transaxle case was heat treated for extra strength, and of course had the getrag gearset, and 4 pin differential. Other than these differences its pretty much the same as the A-520.
These transaxles were filled with dextron ll ATF from the factory. And of course there is no drain plug. There was a chrysler TSB that came out as a result of hard shifting issues even if after the cables were rigged properly. This TSB told the mechanic to pull the left front axle to drain the ATF, reinstall the axle, and to refill with 30 weight motor oil.
I did this to mine, and it was a whole different animal. Shifted like a knife thru butter. Additionally the trapdoor plate (bearing carrier) on the side of the transaxle uses a mild steel reinforcing plate. This distorts under a high load causing gear spread and distruction. FWD performance offers this plate in a heavy duty steel alloy that doesnt allow the distortion.
I currently have another 1988 shelby z t top turbo ll car collecting dust in the corner of my shop. I have a fully rebuilt turbo ll , and rebuilt matching A-555. For it, shelves full of NOS parts in bags and boxes for it when the time comes. It is only a handful of 88 shelbys ordered in the extra cost daytona blue pearlcoat color for 1988 with the t top package making it a 1 of 25 car according to chrysler historical. It also has a factory air bag, these were phased in at the end of 1988 production. 1,690 daytonas, at the end of,1988. This was so rare for 1988 my 1988 factory service manuals dont even list servicing, or schematics on this.
I got into these cars pretty hot and heavy for awhile. I ended up with a ton of spare parts, as well as 2 spare turbo ll engines, and 3 spare A-555 transaxles that are useable LOL.
Eventually i will build this car up, i have almost everything to do it. For now it collects dust, and has boxes of cuda parts piled on it, or leaning against it.