It'll accept a 3.42, 3.08, and 2.73 ring and pinion. Remember that what you do to the rear differential has to be done to the front one. It might have a 700r4, but considering that it's a K20, it'll probably have a three speed. You can swap that in there, but you might consider installing a gear vendor so you can retain the more solid transmission, add gears, and not have to modify anything or add the stand alone computer if you had a 4l80e in mind. Bear in mind that if you swap in those types of gears, it does improve the economy, but it won't tow anything, and it renders those beefier 3/4 ton axles pointless. Unless the truck is pristine, you might consider a K10 that already has a 700R4, smaller axles, and four wheel drive. Then you can swap the gears on both ends and potentially save money. Just my two cents.
