I owned a 1989 F350 CC --> 351,C6,4.10. It was a decent truck, but it was slow and with no overdrive, it would buzz at 3000 RPMs @ 65. It towed just fine. It had 184,000 miles when I got rid of it.
I now have a 2001 F250 CC 4x4 --> 5.4,4R100,3.73. It tows just as good as the 89, but with OD, I can comfortibly drive at 65 MPH +.
I liked them both, but the 89 was more of a pure "truck", whereas the 01 did all of the things the 89 did + act as the family vehicle.
The 89 spent some of time at the dealer (short block replaced under warranty + other issues). I spent a lot of money on engine related issues after the warranty.
The 01 has 108,000-ish miles and has been to the dealer ONCE for plug replacement (@ 106K miles) and a couple recalls. The only real issue I've had was replacing the transmission at 60k for $3500 (ouch).
All in all, I prefer the 2001 over the 1989.