I read somewhere that the stock trannys on these trucks blew up because of over heating without the over drive. never had any issues?
1990 454SS trucks came with a TH400 trans (without overdrive) and 3.73 rear gears
1991-1993 454SS trucks came with a 4L80e trans (with overdrive) and 4.10 rear gears
Both are damn near bulletproof in stock form. The lack of overdrive is not going to cause the trans to blow up. Automatic transmissions overheat due to overloading and insufficient cooling. The factory cooler on these trucks is sufficient for light duty towing, but ANY factory transmission cooler should be updated when towing heavy loads, which will make the transmission run cooler.
Now when people start adding excessive amounts of horsepower and torque
and try to tow without an external cooler, then you may have issues. These transmissions are far superior to the 7004r or 4L80e in stock form.