Welcome to the forum.
Yeah, you put "1982" in the title and describe it as a 1992 in the body of your opening post.
We can assume it's a 1992 as the 1982 "dolphin' used the 22R 4-cylinder --believe it or not as I had a friend who had one!
Yours is the 3VZ V6 engine, correct? You're definitely correct in that a new part is no longer available but I have heard that you can get one from Japan but will be very pricey ...close to or maybe even over $2,000 and that's not including the shipping.
I have seen used ones occasionally on ebay so if you're not in a hurry, you can keep scanning ...I put it in ebay and I don't see that exact ECU for sale currently but maybe you can check with Toyota to see if one with a similar part number is compatible(?). ...ebay page
GO HERE
I see that there are several 89661-35770 that is for the 4x4 but the 2x4 with an automatic is what you'd be looking for with the part # ending in "60" as you've referenced. I see several for a manual transmission and/or 4x4 with manual.
I do see a reconditioned one for $680.00
89661-35760 | ECM (Engine Control Module) for a Toyota Truck (1992 1993)
Since you say that it's still in the shop, is that what they are saying what's needed?