You are correct on all counts Travis. I learned most everything I know on IDIs and diesels generally here and I got into the diesel game when I was 22. I still have a lot to learn. So here's the deal on the gear swap, it will work and you can go as high as 3.55 or even 3.31 maybe which is a good ratio for on the highway, but you'll give up some of your low end grunt. That might be okay depending on if you add a turbo and what transmission you have or if you can add an auxillary transmission, how heavy you want to load this thing etc. The gears are pretty cheap, but you will either have to know how to do the install yourself or know someone who'll do it cheap or it'll bankrupt you in labor charges. An incorrect install can cause accelerated wear on your rear end and bad operating noises. A full on rear end swap may be easier and more cost effective. A transmission swap is pretty routine here, but it can get expensive. You'll need to be able to afford to have it down for a few days at minimum and have all the parts. The hardest part is installing the hydraulics for the master/slave cyls or if you want to be a contrarian like me either designing and building or having someone else make you a mechanical linkage. I iike the old 4 speed boxes because you can grab one from behind a gasser and simply swap out the bellhousing for a diesel. The ZF 5 is much better for fuel economy but it is a one piece casting and diesel or gas specific. You can redrill a 460 bell for a diesel or vice versal, but that's an advanced project and that transmission is not cheap. On the other hand, top gear on a 4 speed is 1:1 so unless you have the cash for a GV overdrive or similar or the fab skills to install a Mitchell or Brownie box auxillary you'll probably under perform in the fuel economy game. They are pretty tough to destroy though. As far as the blowby goes, it goes with the territory of a high compression engine like a diesel, but if it's extreme it's a sign that the engine has seen better days or maybe has a hole in a piston or two if it's to the tune of one or more pistons, one little puff for each is normal. Look for "steam" rising out of the filler neck like a tea kettle, that's normal, epecially if it goes away when you rev the engine past idle. Puffing like a freight train means maybe you should walk away unless it's cheap and you would still be happy with your purchase if you had to replace the engine in the near future. The SCAs I mentioned are critical with the 7.3s because they are a bored 6.9 and the cylinder walls are a little on the thin side compared to what they should be. IH knew about this problem and it was usually ok if the cooling system was maintained with the proper low silicate coolant and diesel/supplemental coolant additives or a diesel rated ELC, but Ford started making 7.3s in 1988 and didn't include this useful bit of info in the diesel owner's supplement until around 1992 when it was too late for a lot of engines. It's probably not a big worry if you buy a truck from a reputable fleet company like Uhaul or a hardcore diesel enthusiast you might find here, but test, don't guess. Lastly, the WMO/WVO fuels are attractive because of high diesel prices, but you need to be sure you have a supply ahead of your needs and before you commit to buying the truck in case that is the only way you can afford to put fuel in it, if you can afford pump fuel you might just not worry about it and work on it as time permits. I burn homebrew biodiesel but it is a lot of work and not without it's difficulties, but I really enjoy it. It gives me a feeling of energy independence but I know if diesel gets really high, none of that WVO supply is really secure and I may be buying WVO for a hefty price and not be much better off than if I was buying pump fuel. Also the glycerine disposal is a potential issue. WVO/SVO burning systems work but you have to put a lot of thought into the design and they work a lot better for vehicles that are worked hard and rarely taken on short trips. DD do best on pump fuel or biodiesel. WMO the jury is still out on it, but it can get you to work/school in a pinch and keep your truck on the road in a fuel crisis, that much is for sure. At what cost is the thing that is up for debate. Whew, sorry to be so long winded but really hope I could help you some.
