I think one out of a junker will be so much more economical than new or reconditioned - it will likely be a no-brainer decision.

I saved this from a post by pageda on 9/2/06: (date of my save, not necessarily of the post)
"you may have a pink label 561 ECU, that is known to fail.
Look for a white label 561 or better yet a 951.
Dan"

If searching the yard yourself, you can look at ECUs in any 240 '89 or later. The '89s came with the pink label 561 however many have been replaced with the white label version or another ECU.

There were different ECUs for cars with/without EGR. Also seems that standard tranny cars had a different ECU which was usually 933. I'd go with the model #s Dan gave.

The number is the last three digits you'll find on the label on the ECU.

I'd really try to swap in a known good working ECU from a friend's car first. You don't want to spend money only to find that didn't solve it. A yard might guarantee their part and let you have another if it's bad - but that doesn't help you if the ECU is not your problem. Any auto-tranny 240 from '89 or later is likely to have an ECU you can use. Also lots of 740s from '89 forward.
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Sven: '89 245 NA, 951 ECU, expanded air dam, forward belly pan reaches oem belly pan, airbox heater upgraded, E-fan, 205/65-15 at 50 psi, IPD sways, no a/c-p/s belt, E-Codes, amber front corner reflectors, aero front face, quad horns, tach, small clock.