I agree with blackdogjenny- the upgrade to the AW70 is most economical. Those prices are pretty good to. The ZF22 you've got is an expensive beast to rebuild.
You might need a driveshaft as well, I'm not sure. You do need the shifter assembly, and an overdrive relay. Not sure if the wiring will be there or not. The shifter is different so you need to get that. Not sure if you will need transmission cooler lines or if the old ones will fit.
If you're pulling parts yourself, get the lines and all the stuff. Remember to unhook the downshift cable at the throttle before pulling the trans.
I've heard prices of $900+ for ZF rebuilds, and that doesn't include removal/installation. The AW's can be had for as little as $100, and are plentiful. A 240 unit will work fine too, but you'll still need the 740 shifter and crossmember. Best to find an 88+ junk 740. The Aw71 in a 740T will work just fine as well.
Good luck with it!
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Rob Bareiss, New London CT ::: '87 244DL/M47- 234K, '82 245T/M46-182K, '89 244DL/AW70- 212K Not too distant past: 86 244DL 215K, 87 244DL 239K, 88 744GLE 233K, 88 244GL 147K, 91 244 183K