The T-5 manual which you can download from the Tremec website covers both WC & NWC and says "Most T-5 trasmission models use Dexron II automatic transmission fluid". I pulled a 1352-145 out of an '88 S-10 and it had gear oil in it but someone had it apart as evidenced by wrench marks, different sealants, and some thrust bearing parts lodged on the magnet in the bottom. I don't think this one is the one that came in the '88. I'm rebuilding it now and planning on putting Dexron III in it. Paul over at 5-speeds.com also says all T-5's use Dexron.
