We have a 93 Chevy 1 ton with 6.5 Turbo Diesel, 5 Speed Manual Transmission. It eats clutches at $1,200 a pop. The warrenty on the last clutch has run out - it is not grinding when you shift into 3 & 4th gears. Should we put in an automatic transmission - if so what one? We pull stock trailers/bumper pull as well as gooseneck. Love this truck but don't like replacing clutches. The recall work has been done on the clutch problem but doesn't seen to help.

You're not using a standard GM clutch are you? There are very good aftermarket clutchs, like ATS and South Bend. http://atsdiesel.com/

We have put in GM clutches and aftermarket clutches. None of them hold. That is why I am looking at converting it to automatic. If we go automatic - what size, etc. should we go with to handle pulling our trailer?

I'd still call ATS diesel in the post above, they have triplelok torque converters that are the best in the business. They can build any auto tranny so they can build one for you that fit behind your diesel. The rebuild trannies behind the 6.5L in H1 Hummers.