[crashz]

First verify that you have a TH350 in your truck. Then verify your gears.

If you have 3.73 or deeper (numerically larger) you would likely benefit from the OD transmission. Taller (numerically lower) will be very driveable with the 3 speed.

The TH350 is a simple easy transmission, that in my opinion, is as strong as a TH400 in a lighter truck without the HP losses. Ironically the TH400 is the only transmission that I've had major issues with.

The 700R4 is not as strong, but has a deeper first gear, and obviously OD. Built appropriately, they last behind big block power and mild off-roading. A later model case and high quality aftermarket parts as well as a good locking torque converter are a must. I had a 4L60E (the electronic 700R4) last for 178K miles and still going strong when I traded my 2004 truck. That truck towed in excess of 7000lbs, plowed snow, hauled more than it should, and had larger tires. The only thing I did was regular maintenance (drain, refill with synthetic fluid and replace filter) every 20K miles and occasionally drained and refilled the pan fluid in between. I also had a transmission temp guage installed and always kept temps below 200 degrees F.

If your TH350 replaced a 700R4, putting one back in its place will be easy. Remove the transfer case (likely a NP208), and remove the adapter and old trans. The 700R4 will bolt right it. The only real trick is to properly adjust the kick-down cable to your carb.