To the Op, if your valve is like mine, if you look down on the valve body from above, you will see a large plug. The relief valve is opposite that plug therefore out the bottom. On mine, the relief is pretty obvious because it is the only adjustable thing. I took out the top plug, spring, and ball and I could look into it an see the relief spool top. That ball and spring are not associated with the relief, they are instead the check valve. But after loosening the two bolts underneath that does hold the relief in, I could push it out from above through the check ball opening.
If this does not sound like your valve, it likely isn't. Mine is a 304 circa 2004.
Probably not related to your problem:
On mine, the problem was that the spring that was supposed to hold the chromed relief spool in position was not strong enough to make it close again due to roughness. I don't know why or how. The tractor was "new to me" and the loader did not work when I bought the tractor. So you just continue onward and upward without trying to guess too much about what the previous owner did.
When I pushed the spool into place with my finger, I'd get resistance and then a click as it moved into position. I repeated that over and over, and realized that can't be right. So I took the block section that contained the relief completely off, and used my drill and some drill rod heavily taped up with vinyl tape to spin the spool in its bore. I used some Mother's aluminum mag polish as my abrasive, and I lapped the relief spool in the bore only until it would move freely in and out without stiction. Then I cleaned it all up exceedingly well to remove all abrasive and put it all back together with new O-rings.
