You folks who visit junkyards need to snag all the Renix ECUs and TCUs that you can.
TCUs are starting to fail at an increasing rate.
ECUs not so much, but grab what you can. They don't make them any more.

If you have an 87 or 88, Grab an 89 or 90 ECU for your rig and save your old one as a spare. More horsepower BTW.
87s had a funkier shifting ECU program. An 88 to 90 is an upgrade.

 

I can't find Renix Jeeps in the yards anymore. They're just getting crushed right away.

I'd always pull a few computers for $8 each when I visited. They'd sell on eBay for $50 to guys who automatically assumed the computer was bad. It's still fairly rare for the TCMs to be bad. I've seen plenty of ECUs with blown injector drivers from shorted wiring harnesses, usually at the flex point between the engine and firewall due to bad motor mounts.