200 overdrive box

To get faster than road gear (direct drive) a cheap way to gain 10% is to find a 190XT four-pinion ring gear and bolt it to the 200 differential carrier and do lots of shimming to make the clearances correct. I know it's been done, because I engineered it in my head (1981) and passed the info on to a local puller (deceased) from Elkader, Iowa. He ran that tractor several years and sold it to someone else.   As far as getting custom gears made for your tranny, good luck, as it seems no one is interested in doing that. There are issues with the design as your input shaft gear has to be larger diameter than the input bearing hole, which means install the countershaft first, then install the input shaft from the rear, then install the mainshaft last. It's been done but not handy. My brother and I built an overdrive box for a friend's 180 (twin turbo) and placed it inside where the Power Director clutch goes. We used Pro-Fab gears and made everything else. We upped the gear ratio once over the years and I think we are currently at 20% over direct.  The tractor is parked and he should sell it. Call if interested after 4PM.   319-360-4788