If it isn't too small, you can get a weldable sprockets. You buy the flange that fits your shaft, find the sprocket with the right size and number of teeth and weld them together. TSC, Fleet Farm, Runnings type stores should have them.
DT is geared and the clutch has been adjusted. IIRC, power to the PTO goes through the clutch on that one, so you could test the clutch with a PTO powered implement if you have one.
If you're just trying to scale down, you can make a chicken the same way as the turkey, just cut the recipe for the stuffing. You could do a ham, smoke a pork butt or brisket. Osso bucco if you have shanks, venison works well for this.
I haven't had problems getting parts for mine but I don't think I'd go gray again. I don't like having to walk into the dealer and asking for a part for an L175, changing the subject when they ask about the serial number etc.
If it's the pressure relief valve, and if the FEL is working well and the 3ph isn't, either plumbing for the FEL has bypassed the pressure relief valve. Might be that the cylinder that runs your 3ph needs a new O-ring.
My L1500DT has the same engine. I read here the glow plugs should ohm out under 10 ohms. Mine were open circuit when I got it and the new ones were a hair under 3. Specs notwithstanding, I'd replace them at 5 or 6. They're cheap. My tach just needed a new cable.
If you're going to be...
If memory serves, there is a serial # break. Before the break, the L185 uses the same pump as the L175 and the L1500, then it changes to a different one. If yours is before the serial # break, I have a thread about it somewhere with the # for the seal. I got my parts from a local dealer. Lano's...