I did a great deal of researd, as I have the 88', 7.3 liter, C6. To convert, it seemed simple enough, but I really estimate it to be about $6500. Doing your own work would shave a lot off of that, but plenty of time and somewhere to work on it. To convert:
Bauman computer (an absolute must). A BUILT E40D. Sun Coast, BTS would be good options. Be sure to build it to 97' specs. The torque converter was a lot of added cost too A good TC for an E4OD would have been between $800 and $1,000. Others may claim to find them cheaper, but why risk such a large investment with a cheap TC? BTS includes one with his E4OD. Last year the quote was $4,500.
. All in all, a great project. David85 (I think that's his handle...you probably saw his posts pop up when you searched this forum) did it with great success apparently. I decided to rebuild my C6. I put in new planetarys, an R servo, Manual valve body, and Torington Bearings. I really wanted a steel caged gear set, as the C6 was all aluminum. To do this, the E4OD, I'm told, would work. My tranny guy has done it. He claimed there was too much difference between 2nd and 3rd gear, and it may over stress my tranny. I agreed and went with the stock, C6 gear set. One thing I realized though...I am putting in a gear splitter (Gear Vendors)...so, I wondered it splitting the gear might have smoothed out the difference from 2nd to 3rd, and compensated for the steep shift. Just thoughts...still wondering. One think Hughes suggested, and if I had the time, I would do is cryo-temper the aluminum gear set. This is supposed to make a substantial difference in any metalurgy, and is well worth the time if it fortifies the aluminum and/or steel as some claim it does.
One of my problems is overheating. I was pulling my D2 Caterpillar up a grade. Went from 1200 above sea level, to 4,310 in about 20 miles. I had to stop. I have a TCI, 28,000, fin and tube cooler with accompanying fan. It was not enough; even in series with my new, aluminum radiator. I have a stacked plate cooler and fan which I'm putting on now, but when it's cold out, I'm wondering how to get my tranny up to temp. Fluid shear with the C6 is a problem, and I would certainly suggest synthetic tranny fluid if you plan to climb and pull loads. Gotta say the N/A, 7.3 sure held it's own on that pull.