Afternoon fellow 720 owners. I am the lucky owner of a 1981 720 2wd with a 3speed automatic tranny. To be fair the transmission shifts pretty smooth. I am commuting with this bad boy and I am driving for about 2 hours a day at 60mph at 3500 RPM. My goal is to put a 4 speed auto in shortly but main question is - is the Z22 motor made to handle being driven at 3500 for long periods of time. Besides the noise I am concerned if I am actually wearing the motor down. My desire to get the auto switch is coming soon but still a couple months away. I have learned so far that I am going to need to shorten the drive shaft for the 4 speed auto. I also notice my gas mileage sucks. This could be because I need to re-build the carb but does anyone have a 4 speed auto in their truck that can shed some light? Gracias

It is fine at 3500rpms, that is where most of us are at going hiway speeds.
I don't know a lot about the 720 automatic transmissions, but I don't recall there being a 4 speed auto for the 720, that doesn't mean there wasn't one.

from what i have read be sure when you replace your tranny that you get one from a truck not a car. there are threads on this. you will know the difference by where reverse is in the shift pattern. thats what i read anyway, but dig around. lots of good info on here. my 720 motorhome has a 5 speed and if your driving hiway i would recommend it. but thats just me.