Last night, I finished installing the K532 back into my 400. Had it out to replace the starter, and cleaned it up while I had it out. I had it all put back together, (well, without the hood & side covers on yet), and fired it up to test. The auxillary hydraulic pump for the loader worked fine, but I wasn't moving anywhere when I put it in high/low and move the speed control.
What I had failed to check, and I probably am not the only one, nor will I be the only one, was that when I removed the engine, the woodruff key had fallen out of the yoke on the input shaft to the hydrostatic pump! I found this after pulling the fender pan, and looking for something wrong. I didn't notice anything, except for when I powered it on, the driveshaft spun, but I could see the hydrostati}c pump wasn't spinning. Just below the yoke, on the cross-member was a lonely woodruff key.
I pondered this for a bit, and decided there would be an easier way than taking the battery, oil cooler, engine, and such back out to get the necessary space. I decided to detach the rear end and transmission/pump assembly from the frame. This only required removal of 7 bolts (I think there should have been an 8th), and I got it back together fairly easily. Using some drift pins here was key to reassembly. The beer sure tasted good after that was done!