“What are the common problems with the 1989 Chevrolet S-10 Blazer 4x4 transmission?”
The ‘89 S-10 Blazer 4×4 with the 4.3 V6 uses the GM 700R4 automatic, and the ones that haven’t been rebuilt usually suffer from a handful of well-known headaches:
Good news: the truck you’re looking at already had a full rebuild (about $8 k worth of work), so those weak points should have been upgraded with fresh 3-4 clutches, a bigger cooler and the TV cable set correctly. If it shifts crisply and the fluid stays cool, you’re in great shape.
Can I help you find similar Blazers or answer anything else?